LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

GIFT    OF 


.. 

\  j 

Class 


A   HISTORY  OF  THE  SCIENCES 

. 

HISTORY 

OF 

CHEMISTRY 


BY 

SIR  EDWARD    THORPE, 

C.B.,  LL.D.,  F.R.S. 

AUTHOR   OP   "  ESSAYS   IN    HISTORICAL   CHEMISTRY,"   "  HUMPHRY   DAVYZ 
POET   AND   PHILOSOPHER,"    "  JOSEPH   PRIESTLEY/'    ETC.,   ETC. 


TWO  VOLUMES 


From  the  Earliest  Times  to  the  Middle  of  the 
Nineteenth  Century 


WITH  ILL  USTRA  TIONS 


G.    P.    PUTNAM'S    SONS 
NEW   YORK   AND    LONDON 

Ebe    ftnicherbocher   jpreaa 
1909 


MAY  29  1911 


pm 


COPYRIGHT,  1909,  BY 
G.  P.  PUTNAM'S   SONS 


This  series  is  published  in  London  by 
THE  RATIONALIST  PRESS   ASSOCIATION,   LIMITED 


PUBLISHERS'  NOTE 

A  HISTORY  OF  THE  SCIENCES  has  been  planned 
to  present  for  the  information  of  the  general 
public  a  historic  record  of  the  great  divisions 
of  science.  Each  volume  is  the  work  of  a 
writer  who  is  accepted  as  an  authority  on  his 
own  subject-matter.  The  books  are  not  to  be 
considered  as  primers,  but  present  thoroughly 
digested  information  on  the  relations  borne  by 
each  great  division  of  science  to  the  changes  in 
human  ideas  and  to  the  intellectual  develop- 
ment of  mankind.  The  monographs  explain 
how  the  principal  scientific  discoveries  have 
been  arrived  at  and  the  names  of  the  workers 
to  whom  such  discoveries  are  due. 

The  books  will  comprise  each  about  200  pages. 
Each  volume  will  contain  from  12  to  1 6  illus- 
trations, including  portraits  of  the  discoverers 
and  explanatory  views  and  diagrams.  Each 
volume  contains  also  a  concise  but  comprehen- 
sive bibliography  of  the  subject-matter.  The 
following  volumes  will  be  issued  during  the 
course  of  the  autumn  of  1909. 

The  History  of  Astronomy.     , 

By  GEORGE  FORBES,  M.A.,  F.R.S.,  M.  Inst. 
C.E. ;  author  of  The  Transit  of  Venus,  etc. 

219143 


The  History  of  Chemistry:  Vol.  I.  circa  2000  B.C. 

to  1850  A.D.     Vol.  II.  1850  A.D.  to  date. 

By  SIR  EDWARD  THORPE,  C.B.,  LL.D.,  F.R.S., 
Director  of  the  Government  Laboratories, 
London;  Professor-elect  and  Director  of 
the  Chemical  Laboratories  of  the  Imperial 
College  of  Science  and  Technology;  author 
of  A  Dictionary  of  Applied  Chemistry. 

To  be  followed  by: 

The  History  of  Geography. 

By  Dr.  JOHN  SCOTT  KELTIE,  F.R.G.S.,  F.S.S., 
F.S.A.,  Hon.  Mem.  Geographical  Societies 
of  Paris,  Berlin,  Rome,  Brussels,  Amster- 
dam, Geneva,  etc.;  author  of  Report  on 
Geographical  Education,  Applied  Geography. 

The  History  of  Geology. 

By  HORACE  B.  WOODWARD,  F.R.S.,  F.G.S., 

Assistant-Director  of  Geological  Survey  of 
England  and  Wales;  author  of  The  Geology 
of  England  and  Wales,  etc. 

The  History  of  Anthropology. 

By  A.  C.  HADDON,  M.A.,  Sc.D.,  F.R.S.,  Lec- 
turer in  Ethnology,  Cambridge  and  Lon- 
don; author  of  Study  of  Man,  Magic  and 
Fetishism,  etc. 

The  History  of  Old  Testament  Criticism. 

By  ARCHIBALD  DUFF,  Professor  of  Hebrew 
and  Old  Testament  Theology  in  the  United 


College,  Bradford;  author  of  Theology  and 
Ethics  of  the  Hebrews,  Modern  Old  Testament 
Theology,  etc. 

The  History  of  New  Testament  Criticism. 

By  F.  C.  CONYBEARE,  M.A.,  late  Fellow  and 
Praelector  of  Univ.  Coll.,  Oxford;  Fellow 
of  the  British  Academy;  Doctor  of  Theol- 
ogy, honoris  causa,  of  Giessen;  Officer  d' 
Academie;  author  of  Old  Armenian  Texts  of 
Revelation,  etc. 

Further  volumes  are  in  plan  on  the  following 
subjects: 

Mathematics  and  Mechanics. 

Molecular  Physics,  Heat,  Life,  and  Electricity. 

Human  Physiology,  Embryology,  and  Heredity. 

Acoustics,  Harmonics,  and  the  Physiology  of 
Hearing,  together  with  Optics  Chromatics,  and 
Physiology  of  Seeing. 

Psychology,  Analytic,  Comparative,  and  Ex- 
perimental. 

Sociology  and  Economics. 

Ethics. 

Comparative  Philology. 

Criticism,  Historical   Research,    and  Legends. 

Comparative  Mythology  and  the  Science  of 
Religions. 


The  Criticism  of  Ecclesiastical  Institutions. 

Culture,  Moral  and  Intellectual,  as  Reflected  in 
Imaginative  Literature  and  in  the  Fine  Arts. 

Logic. 

Philosophy. 

Education. 


CONTENTS 


CHAPTER    I 

THE  CHEMISTRY  OF  THE  ANCIENTS 

Egypt,  the  alleged  birthplace  of  chemistry. 
Origin  of  the  word  "chemistry."  Chemical 
arts  known  to  the  ancients.  Metallurgy  of 
the  ancients.  Chemical  .products  of  the 
Chinese,  Egyptians,  Greeks,  and  Romans. 


CHAPTER    II 

THE  CHEMICAL  PHILOSOPHY  OF  THE  ANCIENTS.  .  19 
Ancient  speculations  as  to  the  origin  and 
nature  of  matter.  Water  the  primal  prin- 
ciple. Thales  of  Miletus.  Persistency  of  his 
doctrine.  Its  influence  on  science.  Theories 
of  Anaximenes,  Herakleitos,  and  Pherekides. 
Fire  as  the  primal  principle.  The  conception 
of  four  primal  principles  —  fire,  air,  water, 
and  earth.  Deification  of  these  by  Empe- 
docles.  Plato  and  Aristotle.  The  doctrine 
of  the  four  Elements.  Influence  of  the  Peri- 
patetic Philosophy  on  science.  Arabian 
science.  Influence  of  the  Moors  in  Spain. 
Atomic  conceptions  of  Anaxagoras,  Leukip- 
pos,  and  Demokritos.  Germs  of  the  atomic 
theory. 

CHAPTER    III 

ALCHEMY     28 

Influence  of  the  Hellenic  mind  on  the  develop- 
ment of  chemistry.     Origin  of  the  idea  of  the 
V 


vi  Contents 

PAGE 

transmutation  of  metals.  Philosophical 
foundation  for  the  belief  in  alchemy.  Al- 
chemistic  theory  of  the  nature  of  metals. 
Origin  of  the  conception  of  the  Philosopher's 
Stone.  Geber.  Association  of  alchemy 
with  astrology.  Rhazes.  Avicenna.  Chem- 
ical processes  and  substances  known  to  the 
Arabian  chemists.  The  Western  Alchemists. 
Albertus  Magnus.  Roger  Bacon.  Raymond 
Lully.  Arnoldus  Villanovanus.  Johannes  de 
Rupecissa.  George  Ripley.  Basil  Valentine. 


CHAPTER    IV 

THE  PHILOSOPHER'S  STONE 46 

Alchemy  in  the  Middle  Ages.  Association 
of  religion  with  alchemy  by  the  Christian 
Church.  Alleged  nature  of  the  Philosopher's 
Stone.  Its  character  described.  Its  power. 
The  Universal  Medicine.  The  Elixir  of  Youth. 
The  Alkahest.  Opponents  of  alchemy: 
Erastius,  Conringius,  and  Kircher.  "  The 
Hermes  of  Germany":  Rudolph  II.  Christ- 
ian princes  who  had  dealings  with  alchemists. 
Fate  of  certain  alchemists.  Persistency  of 
alchemy  and  hermetic  societies.  Lord  Bacon 
on  alchemy. 


CHAPTER    V 

IATRO-CHEMISTRY 57 

Theories  of  the  iatro-chemists.  Paracelsus. 
Doctrine  of  the  tria  prima.  The  Paracelsian 
harmonies.  Libavius.  Van  Helmont.  Syl- 
vius. Willis.  Services  of  iatro-chemistry  to 
science.  Influence  of  iatro-chemistry  on 
technology.  Agricola.  Palissy.  Glauber. 
Chemical  products  made  known  by  the 
alchemists. 


Contents  vii 


CHAPTER   VI  PAGE 

'THE     SCEPTICAL     CHEMIST":  THE    DAWN     OF 

SCIENTIFIC  CHEMISTRY 70 

The  foundation  of  the  Royal  Society  and 
other  scientific  academies.  The  appearance  of 
"The  Sceptical  Chemist":  its  attack  on  the 
doctrines  of  the  Spagyrists.  Boyle:  his  life 
and  character.  His  services  to  learning. 
Kunkel.  Becher.  Mayow.  Lemery.  Horn- 
berg.  Boerhaave.  Stephen  Hales. 


CHAPTER    VII 

PHLOGISTONISM 91 

Becher's  hypothesis  of  the  Terra  Pinguis. 
Its  development  into  the  theory  of  phlogiston. 
Stahl.  '  Phlogiston,  primarily  a  theory  of 
combustion,  becomes  a  theory  of  chemistry. 
Its  general  acceptance  in  Europe  until  the 
last  quarter  of  the  eighteenth  century. 
Prominent  phlogistians.  Pott.  Marggraf. 
Scheele:  his  discoveries.  Duhamel.  Mac- 
quer.  Black:  his  essay  on  Magnesia  Alba. 
Recognition  of  the  individuality  of  carbon- 
dioxide.  Priestley:  his  life  and  character. 
His  discoveries  in  pneumatic  chemistry.  His 
observations  on  the  influence  of  vegetable 
life  on  the  character  of  the  atmosphere. 
Cavendish:  his  life  and  work.  Discovery  of 
composition  of  water.  Influence  of  phlogis- 
tonism  on  the  development  of  chemistry. 
Advances  made  during  the  period  of  phlogis- 
tonism. 

CHAPTER   VIII 

LAVOISIER  AND  LA  REVOLUTION  CHIMIQUE  ....      109 
Downfall    of    phlogistonism.     Lavoisier:  his 
life    and    work.     His    death.     Le    principe 


viii  Contents 


oxygine.  Principle  of  the  conservation  of 
matter.  Chemistry  a  science  of  quantitative 
relations.  Prominent  anti-phlogistians.  Ber- 
thollet.  The  Statique  Chimique.  Fourcroy. 
Vauquelin.  Klaproth.  Proust. 


CHAPTER    IX 

THE  ATOMIC  THEORY 123 

The  atomic  hypotheses  of  the  ancients. 
Newton.  Bergmann.  Lavoisier.  Richter. 
Stochiometry.  John  Dalton:  sketch  of  his 
life  and  character.  How  he  was  led  to  his 
explanation  of  the  laws  of  chemical  combina- 
tion. The  New  System  of  Chemical  Philoso- 
phy. Reception  of  his  theory  by  Davy  and 
Wollaston.  Berzelius:  his  life  and  work. 
His  services  to  chemistry.  First  accurate 
series  of  atomic  weight  determinations. 
Avogadro.  Prout's  hypothesis. 

CHAPTER    X 

THE  BEGINNINGS  OF  ELECTRO-CHEMISTRY 140 

The  Voltaic  Pile.  Electrolytic  decomposi- 
tion of  water  by  Nicholson  and  Carlisle. 
Application  of  voltaic  electricity  to  the  de- 
composition of  the  alkalis  by  Davy.  His  life 
and  work.  Wollaston:  his  life  and  work. 
Electro-chemical  system  of  Berzelius.  Dual- 
ism. Berzelius  reforms  chemical  notation 
and  nomenclature.  Gay  Lussac:  his  life 
and  work.  Thenard:  his  life  and  work. 
Faraday  and  the  law  of  definite  electrolytic 
action. 

CHAPTER    XI 

THE  FOUNDATIONS  OF  ORGANIC  CHEMISTRY....      154 
Nicolas  Lemery  divides  chemistry  into  its  two 
main    branches    of    inorganic    and    organic 


Contents  ix 

PAGE 

chemistry.  State  of  knowledge  of  products 
of  organic  origin  during  the  early  years  of  the 
nineteenth  century.  Animal  chemistry. 
Doctrine  of  vital  force.  Wohler's  synthesis 
of  urea.  Organic  chemistry  is  the  chemistry 
of  the  carbon  compounds.  Early  attempts 
at  organic  analysis  by  Lavoisier,  Berzelius, 
Gay  Lussac,  and  Thenard.  Liebig.  Dis- 
covery of  isomerism  and  allotropy.  Cyano- 
gen. Theory  of  compound  radicals.  Etherin 
theory  of  Dumas  and  Boullay.  Memoir  of 
Liebig  and  Wohler  on  oil  of  bitter  almonds. 
Benzoyl  theory.  Investigation  of  alkarsin 
by  Bunsen.  Cacodyl.  Discovery  of  zinc 
ethyl  by  Frankland. 


CHAPTER   XII 

THE  RISE  OP  PHYSICAL  CHEMISTRY    170 

Relations  of  chemistry  to  physics.  Relations 
of  heat  to  chemical  phenomena.  Improve- 
ments in  the  mercurial  thermometer. 
Newton.  Shuckburgh.  Brooke  Taylor. 
Cavendish.  Black.  Discovery  of  latent 
heat  by  Black.  Discovery  of  specific  heat. 
Experiments  of  Lavoisier  and  Laplace.  Law 
of  Dulong  and  Petit :  its  value  in  determining 
atomic  weights.  Specific  heat  of  compounds. 
Neuman.  Discovery  of  isomorphism  by 
Mitscherlich.  Foreshadowing  of  the  kinetic 
theory  of  gases.  Discovery  of  the  law  of 
gaseous  diffusion  by  Graham.  Liquefaction 
of  gases.  Monge  and  Clouet.  Northmore. 
Faraday.  Value  of  a  knowledge  of  weights 
of  unit  volumes  of  gases  in  determining  their 
molecular  weights.  Methods  of  vapour- 
determination  by  Dumas  and  Gay  Lussac. 
Dalton  and  Henry's  law  of  gaseous  solubility. 


x  Contents 

PAGE 

Work  of  Schroder  and  Kopp  on  volume  rela- 
tions of  liquids  and  solids.  Connection 
between  the  chemical  nature  of  a  liquid  and 
its  boiling-point. 

BIBLIOGRAPHY 183 

INDEX , , 187 


HISTORY    OF   CHEMISTRY 


CHAPTER   I 
THE   CHEMISTRY  OF  THE   ANCIENTS 

/CHEMISTRY,  as  an  art,  was  practised  thou- 
^-^  sands  of  years  before  the  Christian  era;  as  a 
science,  it  dates  no  further  back  than  the  middle 
of  the  seventeenth  century.  The  monumental 
records  of  Egypt  and  the  accounts  left  us  by 
Herodotus  and  other  writers  show  that  the 
ancient  Egyptians,  among  the  earliest  nations 
of  whom  we  have  any  records,  had  a  considerable 
knowledge  of  processes  essentially  chemical  in 
their  nature.  Their  priests  were  adepts  in  cer- 
tain chemical  arts,  and  chemical  laboratories 
were  occasionally  attached  to  their  temples,  as  at 
Thebes,  Memphis,  and  Heliopolis.  It  is  to  be 
supposed,  too,  that  in  a  cultured  class,  as  the 
priesthood  undoubtedly  was,  there  would  be  now 
and  again  curious  and  ingenious  persons  who 
would  speculate  on  the  nature  and  causes  of  the 
phenomena  which  they  observed.  But  there  is  no 


2  History  of  Chemistry 

certain  evidence  that  the  Egyptians  ever  pur- 
sued chemistry  in  the  spirit  of  science,  or  even 
in  the  manner  in  which  they  and  the  Chaldaeans 
followed,  for  example,  astronomy  or  mathemat- 
ics. The  operations  of  chemistry  as  performed 
by  them  were  of  the  nature  of  manufacturing 
processes,  empirical  in  character  and  utilitarian 
in  result.  It  was  comparatively  late  in  the 
world's  history  that  men  were  found  willing  to 
occupy  themselves  in  chemical  pursuits  in  order 
to  gain  an  insight  into  the  nature  of  chemical 
change,  and  to  learn  the  causes  and  conditions 
of  its  action. 

Although  we  have  cited  the  ancient  Egyptians 
as  practising  the  chemical  arts,  there  is  no  proof 
that  these  arts  actually  originated  with  them. 
China,  India,  Chaldaea  have  each  in  turn  been 
regarded  as  the  birthplace  of  the  various  tech- 
nical processes  from  which  chemistry  may  be 
said  to  have  taken  its  rise.  Nevertheless,  it  is  ' 
mainly  from  Egyptian  records,  or  from  writings 
avowedly  based  on  information  from  Egyptian 
sources,  that  such  knowledge  as  we  possess  of  the 
earliest  chemical  processes  is  derived.  It  is 
significant  that  the  word  " chemistry"  has  its 
origin  in  chemi,  "the  black  land,"  the  ancient 
name  for  Egypt.  The  art  itself  was  constantly 
spoken  of  as  the  "  Egyptian  art.  " 

"The   word    chemistry,1'    says    Boerhaave    in 
the  Prolegomena  of  his  New  Method  of  Chemistry 


The  Chemistry  of  the  Ancients      3 

(Shaw    and    Chambers's    translation,  .  London, 

1727). 

in  Greek  should  be  wrote  %y/J.fa ,  and  in  Latin  and 
English  chemia  and  chemistry;  not  as  usual, 
chymia  and  chymistry. 

The  first  author  in  whom  the  word  is  found 
is  Plutarch,  who  lived  under  the  Emperors 
Domitian,  Nerva,  and  Trajan.  That  philoso- 
pher, in  his  treatise  of  Isis  and  Osiris,  takes 
occasion  to  observe  that  Egypt,  in  the  sacred 
dialect  of  the  country,  was  called  by  the  same  name 
as  the  black  of  the  eye  —  viz.,  %1}}M<* — by  which 
he  seems  to  intimate  that  the  word  chemia  in 
the  Egyptian  language  signified  black,  and  that 
the  country,  Egypt,  might  take  its  denomination 
from  the  blackness  of  the  soil. 

But  [continues  Boerhaave]  the  etymology  and 
grammatical  signification  of  the  name  is  not  so 
easily  dispatched.  The  critics  and  antiquaries, 
among  whom  it  has  been  a  great  subject  of 
inquiry,  will  not  let  it  pass  without  some  further 
disquisition.  Instead  of  black,  some  will  have 
it  originally  denote  secret,  or  occult;  and  hence 
derive  it  from  the  Hebrew  chaman,  or  haman  — 
a  mystery,  whose  radix  is  cham.  And,  accord- 
ingly, Plutarch  observes  that  Egypt,  in  the 
same  sacred  dialect,  is  sometimes  wrote  in 
Greek  %aj[iia  — chamia;  whence  the  word  is  easily 
deduced  further  from  Cham,  eldest  son  of  Noah, 
by  whom  Egypt  was  first  peopled  after  the 
deluge,  and  from  whom,  in  the  Scripture  style, 
it  is  called  the  land  of  Cham,  or  Chem.  Now, 
that  chaman,  or  haman,  properly  signifies  secret 
appears  from  the  same  Plutarch,  who,  mention- 
ing an  ancient  author  named  Menethes  Sibonita, 
who  had  asserted  that  Ammon  and  Hammon 
were  used  to  denote  the  god  of  Egypt,  Plutarch 
takes  this  occasion  to  observe  that  in  the 
Egyptian  language  anything  secret  or  occult 


History  of  Chemistry 

Wa§  called  by  the  same  name,  a/A/xov  —  Ham- 
mon.  .  .  .  Lastly,  the  learned  Bo  chart,  keeping 
to  the  same  sense  of  the  word,  chooses  to  derive 
it  from  the  Arabic  chema,  or  kema  —  to  hide; 
adding  that  there  is  an  Arabic  book  of  secrets 
called  by  the  same  name  Kemi. 

From  the  whole  of  which  Boerhaave  gathers  that 
chemistry  was  thus  originally  denominated  be- 
cause it  was  considered  of  old  as  "not  fit  to  be 
divulged  to  the  populace,  but  treasured  up  as  a 
religious  secret." 

If  we  are  to  credit  Zozimus  the  Panopolite, 
who  is  said  to  have  lived  about  the  beginning  of 
the  fifth  century,  there  were  sound  reasons  for 
thus  treasuring  up  chemistry  as  a  religious 
secret,  since,  as  it  sprang  from  the  pretium 
amoris,  its  origin  was  not  too  reputable.  "What 
the  divine  writings  relate  is  that  the  angels, 
enflamed  with  the  desire  of  women,  instructed 
'em  in  all  the  works  and  mysteries  of  nature. 
For  which  indiscretion  they  were  excluded  hea- 
ven, as  having  taught  men  things  unfit  for  'em 
to  know."  And  Scaliger  asserts  that  "Hermes 
testifies  as  much;  and  all  our  learning,  both  open 
and  occult,  confirms  the  account. "  But  who 
Hermes  was,  adds  that  author,  is  hard  to  say, 
for  none  of  his  writings  has  survived  to  our  age, 
"that  lately  published  in  Italy  under  the  name 
of  Her-mes  Trismegistus  being  a  manifest  forgery." 

This  legend  of  the  "  feministic  "  origin  of  chem- 
istry is  in  reality  much  older  than  the  fifth  cen- 


The  Chemistry  of  the  Ancients      sj 

tury  of  our  era,  and  is  but  a  variant  of  that 
which,  according  to  Jewish  writers,  led  to  the 
expulsion  of  man  from  Paradise.  A  similar  myth 
was  current  among  the  Phoenicians,  Persians, 
Greeks,  and  Magi.  We  trace  it  in  the  legend  of 
Sibylla,  who  demanded,  as  the  price  of  her  favour 
to  Phoebus,  not  t  only  length  of  years,  but  a 
knowledge  of  the  divine  arcanum.  Some  of  the 
ecclesiastics  who  elaborated  these  myths  are 
•particular  in  their  accounts  of  the  mysteries  thus 
imparted.  They  included  the  use  of.  charms,  a 
knowledge  of  gold  and  silver  and  precious  stones, 
the  art  of  dyeing,  of  painting  the  eyebrows, 
etc.  —  the  kind  of  arcana,  in  fact,  which  women 
in  all  ages  were  presumably  most  keen  to  know. 
It  is,  however,  significant  that  in  all  allusions  to 
chemia,  even  after  the  translation  of  the  seat  of 
the  Roman  Empire  to  Constantinople,  it  is  im- 
plied that  a  knowledge  of  it  was  a  sacred  mystery 
to  be  known  only  to  the  priesthood,  and  jealously 
guarded  by  them.  It  was  characteristic  of 
writers  who  had  affixed  an  eternal  stigma  on  Eve 
to  make  the  sex  in  general  answerable  for  an 
illicit  knowledge  of  "things  unfit  for  men  to 
know." 

For,  in  reality,  chemistry  originated  with  men, 
and  it  was  not  so  much  in  the  love  of  women  as 
of  wine  that  it  took  its  rise. 

The  manufacture  of  alcohol  by  processes  of 
fermentation  is  probably  the  oldest  of  the  chem- 


6  History  of  Chemistry 

ical  arts.  The  word  wine  means,  in  fact,  a  pro- 
duct of  fermentation.  Mosaic  history  relates  that 
Noah,  soon  after  he  got  to  dry  land, "planted  a 
vineyard  and  drank  of  the  wine,"  with  results 
that  would  appear  to  show  that  the  potency  of 
wine  was  not  unfamiliar  to  him.  Diodorus 
Siculus,  who  studied  Egyptian  antiquities  when 
Egypt  was  a  Roman  province,  states  that  the 
ancient  Egyptians  ascribed  the  origin  of  wine  to 
Osiris.  It  was  a  sacrificial  offering  even  in  the 
earliest  times,  as  was  bread.  Wine  seems  to 
have  been  prepared  by  the  Chinese  as  far  back 
as  the  time  of  the  Emperor  Yii,  circa  2220  B.C. 
Beer  was  manufactured  in  Egypt  in  the  time 
of  Senwosret  in.  (Sesostris)  B.C.  1880. 

The  Egyptians  were  skilled  in  dyeing  and  in 
the  manufacture  of  leather,  and  in  the  produc- 
tion and  working  of  metals  and  alloys.  They 
were  familiar  with  the  methods  of  tempering  iron. 
They  made  glass,  artificial  gems,  and  enamels. 
The  oldest  known  enamel  was  found  as  an  amu- 
let on  the  Egyptian  Queen  Aahotep  (1700  B.C.), 
and  glass  beads  were  made  before  the  time  of 
Thutmosis  in.  (1475  B.C.).  The  Jews  knew  of 
gold,  silver,  copper,  iron,  lead,  and  tin.  Indeed, 
it  is  through  them  and  the  Phoenicians,  who  were 
among  the  earliest  of  traders,  that  Europe  was 
gradually  made  acquainted  with  many  technical 
products  of  Eastern  origin. 

The  beginnings  of  the  art  of  extracting  and 


The  Chemistry  of  the  Ancients      7 

working  of  metals  are  lost  in  the  mists  of  anti- 
quity; the  chemistry  of  metals,  indeed,  has  been 
said  to  be  almost  coeval  with  mankind.  Diod- 
orus  Siculus  found  traditions  in  Egypt  as  to  the 
first  inventor  of  metallurgical  processes  identical 
with  that  of  the  son  of  Lamech  and  Zillah,  Tubal- 
cain,  or  Tuval-cain,  of  the  Hebrews — the  Vulcan 
of  the  Romans. 

Gold  was  undoubtedly  one  of  the  earliest  met- 
als to  be  made  use  of  by  men,  as  it  probably  was 
one  of  the  first  to  be  discovered.  It  occurs  free 
in  nature,  and  is  met  with  in  many  rocks  and  in 
the  sands  of  rivers.  Its  colour,  lustre,  and  density 
jwould  early  attract  attention  to  it ;  and  its  mal- 
leability and  ductility  and  the  ease  with  which 
it  could  be  fashioned,  together  with  its  unalter- 
ability,  would  render  it  valuable.  Ethiopian 
and  Nubian  gold  were  known  from  the  earliest 
times,  and  quartz  crushing  and  gold  washing 
v  were  practised  by  the  Egyptians.  Representa- 
tions of  these  processes  have  been  found  on 
Egyptian  tombs  dating  from  2500 B.C.  Gold-wire 
was  used  by  the  Egyptians  for  embroidery,  and 
they  practised  plating,  gilding,  and  inlaying  as 
far  back  as  2000  B.C. 

Silver  also  was  employed  by  them,  and  appears, 
like  gold,  to  have  been  coined  into  money.  It 
was  originally  known  as  "  white  gold."  Some  of 
the  oldest  coins  in  existence  are  alloys  of  silver 
and  gold,  obtained  probably  by  the  fusion  of 


8  History  of  Chemistry 

naturally  occurring  argentiferous  gold,  such  as 
the  pale  gold  of  the  Pactolus."  Such  an  alloy 
was  termed  electrum,  from  its  resemblance  in 
colour  to  amber. 

Copper  is  also  found  to  a  limited  extent  in  the 
metallic  state,  but  probably  the  greater  part  of 
that  used  by  the  ancients  was  obtained  from  its 
ores,  which  are  comparatively  abundant  and 
readily  smelted.  It  was  also  used  for  coinage  by 
the  Egyptians,  and  was  fashioned  by  them  into  a 
variety  of  utensils  and  implements.  The  older 
writers  drew  no  clear  distinction  between  copper, 
bronze,  and  brass,  and  the  terms  designating 
them — (Bs  and  %a  XKOS — are  frequently  employed; 
as  by  Pliny,  indiscriminately.  The  statement  in 
Deut.  viii.  9  —  "  Out  of  whose  hills  thou  mayest 
dig  brass"  —  obviously  cannot  mean  an  alloy 
of  copper  and  zinc,  since  this  does  not  occur 
naturally. 

Pure  copper  is  too  soft  a  metal  to  be  used  for 
swords  and  cutting  instruments,  but  copper  ores 
frequently  contain  associated  metals,  as,  for 
example,  tin,  which  would  confer  upon  the 
copper  the  necessary  hardness  to  enable  it  to  be 
fashioned  into  weapons.  Such  copper  would  be 
of  the  character  of  bronze,  and  it  was  known  to 
the  early  workers  that  the  nature  of  the  metal 
was  greatly  modified  by  the  selection  of  ores 
from  particular  localities.  It  was  compara- 
tively late  in  the  metallurgical  history  of  copper 


The  Chemistry  of  the  Ancients      9 

that  bronze  was  produced  by  knowingly  adding 
tin  to  the  metal. 

Copper  was  largely  used  by  the  Romans, 
who  obtained  it  from  Cyprus;  it  was  known  to 
them  as  CBS  Cyprium,  and  eventually  Cuprum, 
whence  we  obtain  the  chemical  symbol  Cu. 
What  the  Romans  called  CBS  was  found  also  at 
Chalkis,  in  Eubcea,  whence  jo^/cos,  the  Greek 
word  for  copper. 

Aurichakum,  or  golden  copper  —  that  is, 
brass  —  was  well  known  to  the  early  workers  in 
copper,  and  was  made  in  Pliny's  time  by  heating 
together  copper,  cadmia  (calamine),  and  char- 
coal. 

Bell  metal  was  employed  by  the  Assyrians,  and 
bronze  was  cast  by  the  Egyptians  for  the  manu- 
facture of  mirrors,  vases,  shields,  etc.,  as  far  back 
as  2000  B.C.  Statuary  bronze,  largely  used  by 
the  Romans,  usually  contained  more  or  less 
lead. 

Tin,  which  was  also  .known  to  the  early 
Egyptians,  would  appear  to  ,have  been  first 
obtained  from  the  East  Indies,  and  to  have 
been  known  under  the  Sanscrit  name  of 
Kastira  (Kas,  to  shine),  whence  we  have  the 
Arabic  word  for  tin,  Kasdir,  and  the  Greek 
KaaaiTspos,  used  by  Homer  and  Hesiod.  Tin 
ores  are  found  in  Britain  (Cornwall),  and  were 
brought  thence  by  the  Phoenicians.  The  group 
of  islands,  including  the  Scilly  Islands  and 


io  History  of  Chemistry 

the  larger  island  to  the  east  (Britain),  was 
known  to  the  Romans  as  the  Insulcs  Cassiterides. 

Pliny  states  that  the  tin  is  found  in  grains  in 
alluvial  soil,  from  which  it  is  obtained  by  wash- 
ing; but  he  gives  no  description  of  the  method  of 
smelting.  The  Latin  word  for  tin  was  stannum; 
it  was  also  known  as  plumbum  album,  in  contra- 
distinction to  lead,  which  was  called  plumbum 
nigrum.  Tin  was  used  by  the  Romans  for 
covering  the  inside  of  copper  vessels,  and  was 
also  occasionally  employed  in  the  construction 
of  mirrors. 

Lead  was  well  known  to  the  Egyptians.  In 
Pliny's  time  it  was  mainly  procured  from  Spain 
£,nd  from  Britain  (Derbyshire).  Leaden  pipes 
were  used  by  the  Romans  for  the  conveyance 
of  water,  and  sheet  lead  was  employed  by 
them  for  roofing  purposes.  The  Romans  were 
also  aware  of  alloys  of  lead  and  tin.  Argen- 
tarium  was  composed  of  equal  parts  of  lead  and 
tin;  tertiarium,  used  as  a  solder,  consisted  of  two 
parts  of  lead  and  one  part  of  tin. 

Iron,  although  now  the  most  important  of  the 
common  metals,  was  not  in  general  use  until 
long  after  the  discovery  of  gold,  silver,  and 
copper.  This  was  probably  due  to  the  fact  that, 
although  its  ores  are  relatively  abundant  and 
widely  distributed,  its  extraction  as  a  metal 
demanded  greater  skill  and  more  appliances 
than  were  possessed  by  the  earlier  races.  Metal- 


The  Chemistry  of  the  Ancients    n 

lie  iron  was,  however,  well  known  to  the  Egypt- 
ians, who  employed  it  in  the  manufacture  of 
swords,  knives,  axes,  and  stone-chisels,  both  as 
malleable  iron  and  as  steel.  Steel  was  also 
known  to  the  Chinese  as  far  back  as  2220  B.C., 
and  they  were  acquainted  with  the  methods  of 
tempering  it.  The  good  quality  of  Chinese  steel 
caused  it  to  be  highly  prized  by  Western  nations. 
The  earliest  people  to  smelt  iron  are  supposed  to 
have  been  the  Chalybes,  a  nation  inhabiting  the 
neighbourhood  of  the  Black  Sea;  it  is  from  them 
that  the  ancient  name  for  steel  —  ckalybs  —  is 
derived,  and  also  our  word  ''chalybeate." 

Mercury  has  long  been  known,  but  there  is  no 
evidence  that  the  ancient  Egyptians  were  aware 
of  its  existence,  or  it  would  probably  have  been 
mentioned  by  Herodotus.  It  was  familiar  to 
Aristotle,  and  its  mode  of  manufacture  from 
cinnabar  is  described  by  Theophrastus  (320  B.C.), 
who  terms  it  " liquid  silver."  Processes  of 
amalgamation  were  known  to  Pliny,  who  notes 
the  readiness  with  which  mercury  dissolves  gold. 
Pliny  appears  to  distinguish  the  native  metal 
found  in  Spain,  which  he  terms  argentum  vivum 
(quicksilver) ,  from  that  obtained  by  sublimation 
or  distillation  from  cinnabar,  which  he  calls 
hydrargyrum,  from  which  we  get  the  chemical 
symbol  for  mercury  Hg. 

A  considerable  number  of  metallic  compounds 
were  known  to  the  ancients,  and  were  employed 


12  History  of  Chemistry 

by  them  as  medicines  and  as  pigments.  The 
oxides  of  copper,  known  as  flos  ceris,  and  scoria 
cerisj  obtained  by  heating  copper  bars  to  redness 
and  exposing  them  to  air,  were  used  as  eschar- 
otics.  Verdigris,  or  aerugo,  was  made  by  the  same 
methods  as  now.  Blue  vitriol,  or  chalcantum, 
is  described  by  Pliny,  who  says  that  the  blue 
transparent  crystals  are  formed  on  strings  sus- 
pended in  its  solution. 

Chrysocolla,  malachite,  or  copper  carbonate, 
was  used  as  a  green  pigment.  The  blue  Kvavos  of 
the  Greeks,  or  coeruleum  of  the  Romans,  was 
obtained  by  fritting  together  alkali,  sand,  and 
oxide  of  copper.  Botryitis,  placitis,  ony chilis, 
ostracitis,  were  varieties  of  cadmia  or  oxide  of 
zinc,  obtained  by  calcining  calamine,  and  were 
used  in  the  treatment  of  ulcers,  etc.  Molybdena, 
which  was  the  Latin  name  for  litharge,  was 
employed  externally  as  an  astringent  and  in  the 
manufacture  of  plaster.  The  lead  plaster  em- 
ployed by  Roman  surgeons  was  practically 
identical  in  character  and  mode  of  preparation 
with  that  in  use  to-day.  Cerussa,  or  white  lead, 
was  made  as  now  by  exposing  sheets  of  lead  to 
the  fumes  of  vinegar.  It  was  used  in  medicine, 
as  a  pigment,  and  in  the  preparation  of  cosmetics. 
Cerussa  usia  was  probably  red  lead.  Its  present 
name  of  minium  was  originally  applied  to  cinna- 
bar, the  red  sulphide  of  mercury,  which  was 
frequently  adulterated  with  red  lead. 


The  Chemistry  of  the  Ancients    13 

Cinnabar,  formerly  obtained  from  Africa,  and, 
by  the  Romans,  from  Spain,  was  also  used 
externally  in  medicine,  and  was  a  highly  prized 
pigment,  whose  value  was  known  to  the  Chinese 
from  very  early  times.  The  black  sulphide  of 
antimony,  the  stimmi  and  stibium  of  Dioscorides 
and  Pliny,  was  employed  by  women  in  Asia, 
Greece,  and  latterly  in  Western  Europe,  and  is 
still  so  used  in  the  East,  for  blackening  their 
eyelashes.  Preparations  of  antimony  were  used 
in  medicine.  Realgar,  the  scarlet  sulphide  of 
arsenic,  the  sandarach  of  Aristotle,  and  the 
arrenichon  of  Theophrastus,  was  employed  as  a 
pigment,  and  also  in  medicine,  both  internally 
and  externally.  The  yellow  sulphide  of  arsenic 
or  auri  pigmentum  (orpiment) ,  was  also  used  for 
the  same  purposes. 

A  variety  of  yellow  and  red  ochres,  in  addition 
to  the  pigments  above  mentioned,  were  used  by 
painters,  such/ as  rubrica,  an  iron  ochre  of  a  dark 
red  colour,  and  sinopis,  or  reddle,  obtained  from 
Egypt,  Lemnos,  and  the  Balearic  Isles.  Oxides 
of  manganese  were  used  as  brown  pigments. 
The  white  pigment,  paratonium,  was  probably 
meerschaum.  Melinum  was  a  variety  of  chalk 
found  in  Samos.  The  ancients  were  well 
acquainted  with  indigo  and  madder,  and  with 
the  method  of  manufacturing  lakes,  which  was 
employed  by  Grecian  artists. 

The  famous  purpurissum  was  chalk  or  clay 


14  History  of  Chemistry 

stained  by  immersion  in  a  solution  of  Tyrian 
purple.  Atramentum  was  lamp-black:  ivory- 
black  was  used  by  Apelles,  and  was  known  as 
elephantinum.  The  ink  of  the  ancients  consisted 
of  lamp-black  suspended  in  a  solution  of  gum  or 
glue.  The  atr amentum  indicnm,  imported  from 
the  East,  was  indentical  with  China  ink. 

The  ancients  were  well  skilled  in  the  art  of 
dyeing,  and  even  of  calico  printing.  The 
Tyrians  produced  their  famous  purple  dye  as 
far  back  as  1500  B.C.  It  was  obtained  from 
shell-fish,  mainly  species  of  Murex,  inhabiting 
the  Mediterranean.  Tyrian  purple  has  been 
shown  to  be  dibrom-indigo,  and  to  have  been 
produced  by  the  action  of  air  and  light  upon 
the  juices  exuded  from  the  shell-fish.  The  fine 
linen  of  the  Old  Testament  was  probably  cotton, 
for  the  production  of  which  Egypt  was  long  cele- 
brated. That  the  Egyptians  were  acquainted  with 
the  use  of  mordants  seems  evident  from  the  fol- 
lowing passage  from  Pliny,  quoted  by  Thomson : — 

There  exists  in  Egypt  a  wonderful  method  of 
dyeing.  The  white  cloth  is  stained  in  various 
places,  not  with  dye  stuffs,  but  with  substances 
which  have  the  property  of  absorbing  colours; 
these  applications  are  not  visible  upon  the  cloth, 
but  when  they  are  dipped  into  a  hot  caldron 
of  the  dye  they  are  drawn  out  an  instant  after 
dyed.  The  remarkable  circumstance  is  that, 
though  there  be  only  one  dye  in  the  vat,  yet 
different  colours  appear  upon  the  cloth;  nor 
can  the  colour  be  afterwards  removed. 


The  Chemistry  of  the  Ancients    15 

This  passage  accurately  describes  the  process  of 
madder  dyeing  on  cotton,  whereby  a  variety  of 
fast  colours  —  reds,  browns  and  purples  —  can 
be  obtained  from  frhe  same  vat  by  the  employ- 
ment of  different  mordants,  such  as  alumina, 
oxide  of  iron,  or  oxide  of  tin,  etc. 

Glass  has  been  known  from  very  early  times. 
Representations  of  glass-blowing  were  found 
on  the  monuments  of  Thebes  and  Beni  Hassan, 
and  large  quantities  of  glass  were  exported  to 
Greece  and  Rome  from  Egypt,  mainly  by  Phoe- 
nicians. Aristophanes  mentions  it  as  hyalos, 
and  speaks  of  it  as  the  beautiful  transparent 
stone  used  for  kindling  fire.  The  Egyptians 
made  use  of  various  metallic  oxides  in  colour- 
ing glass.  The  k&matinon  of  Pliny  was  a  red 
glass  coloured  with  cuprous  oxide.  Cupric  oxide 
was  used  to  colour  glass  green ;  and  ancient  blue 
glass  has  been  found  to  contain  cobalt.  The 
costly  vasa  murrhina  of  the  Romans,  obtained 
from  Egypt,  probably  consisted  of  fluorspar, 
identical  with  the  Blue  John  of  the  Derbyshire 
mines. 

Stoneware  has  been  made  from  time  imme- 
morial, and  the  Chinese  have  manufactured 
porcelain  from  very  remote  periods.  Bricks  and 
tiles  were  made  by  the  Romans,  and  mortar  and 
stucco  were  employed  by  the  ancient  Egyptians. 
Soap  (sapo)  is  mentioned  by  Pliny,  but  its 
detergent  properties  were  apparently  unknown 


1 6  History  of  Chemistry 

to  him.  It  appears  to  have  been  first  made  by 
the  Gauls,  who  prepared  it  from  the  ashes  of  the 
beech  and  the  fat  of  goats,  and  used  it  as  a 
pomatum,  as  did  the  jeunes^e  d'oree  of  Rome. 
Wood  ashes,  as  well  as  natron,  were,  however, 
used  by  the  ancients  for  their  cleansing  prop- 
erties. 

Starch,  acetic  acid,  sulphur,  alumen  or  crude 
sulphate  of  alumina,  beeswax,  camphor,  bitumen, 
naphtha,  asphalt,  nitrum  (carbonate  of  soda), 
common  salt,  and  lime,  were  all  known  to  the 
Egyptians,  and  were  used  by  them  for  many 
of  the  purposes  in  which  they  are  employed 
to-day. 

It  will  be  evident  from  this  brief  survey  that 
the  ancients  possessed  a  considerable  acquain- 
tance with  many  operations  of  technical  chemis- 
try; but,  although  they  must  necessarily  have 
accumulated  a  large  amount  of  knowledge,  very 
little  has  come  down  to  us  concerning  the  mode 
in  which  their  processes  were  conducted,  or  as  to 
the  precautions  they  employed  to  ensure  uni- 
form results.  Their  methods  were  probably 
jealously  guarded  and  handed  down  by  succes- 
sive members  of  the  crafts  as  precious  secrets. 
The  experienced  masters  of  these  crafts  must 
have  met  with  many  strange  and  perplexing 
phenomena  in  the  course  of  their  operations,  and 
a  spirit  of  inquiry  must  thereby  at  times  have 
been  awakened.  But,  under  the  conditions  in 


The  Chemistry  of  the  Ancients    17 

which  their  industries  were  prosecuted,  the  scien- 
tific spirit  was  not  free  to  develop,  for  science* 
depends  essentially  upon  free  intercommunica- 
tion of  facts  and  the  spread  of  knowledge  of 
natural  phenomena.  Moreover,  the  great  intel- 
lects of  antiquity,  for  the  most  part,  had  little 
sympathy  with  the  operations  of  artisans,  who, 
at  least  among  the  Greeks  and  Romans,  were, 
for  the  most  part,  slaves.  Philosophers  taught 
that  industrial  work  tended  to  lower  the  stand- 
ard of  thought.  The  priests,  in  most  ages,  have 
looked  more  or  less  askance  at  attempts,  on  the 
part  of  the  laity,  to  inquire  too  closely  into  the 
causes  of  natural  phenomena.  The  investiga- 
tion of  nature  in  early  times  was  impossible 
for  religious  reasons.  There  was  an  outcry  in 
Athens  when  the  thunderbolts  of  Zeus  were 
ascribed  to  the  collision  of  clouds.  Anaxagoras, 
Diogenes  of  Apollonia,  Plato,  Aristotle,  Diag- 
oras,  and  Protagoras  were  charged  by  the  priests 
with  blasphemy  and  driven  into  exile.  Prodi- 
kos,  who  deified  the  natural  forces,  as  did 
Empedokles  the  primal  elements,  was  executed 
for  impiety.  Sacerdotalism  in  Athens  had  no 
more  sympathy  with  science  than  had  the  Holy 
Congregation  in  Italy  when  it  banned  the  writ- 
ings of  Copernicus,  Kepler,  and  Galileo,  and  sent 
Giordano  Bruno  to  the  stake.  The  educated 
Greeks  had  no  interest  in  observing  or  in  ex- 
plaining the  phenomena  of  technical  processes. 


i8  History  of  Chemistry 

However  prone  they  might  be  to  speculation, 
they  had  no  inclination  to  experiment  or  to 
engage  in  the  patient  accumulation  of  the 
knowledge  of  physical  facts.  "You  Greeks,'* 
says  Plato  in  one  of  his  Dialogues,  "are  ever 
children,  having  no  knowledge  of  antiquity,  nor 
antiquity  of  knowledge!"  The  influence  of  a 
spurious  Aristotelianism,  which  lasted  through 
many  centuries  and  even  beyond  the  time  of 
Boyle,  was  wholly  opposed  to  the  true  methods 
of  science,  and  it  was  only  when  philosophy  had 
shaken  itself  free  from  scholasticism  that  chem- 
istry, as  a  science,  was  able  to  develop. 


CHAPTER    II 
THE   CHEMICAL  PHILOSOPHY  OF  THE  ANCIENTS 

C  PECULATIONS  as  to  the  origin  and  nature 
^  of  matter,  and  as  to  the  conditions  and  forces 
which  affect  it,  are  to  be  found,  more  or  less 
imperfectly  developed,  in  the  oldest  systems  of 
philosophy  of  which  we  have  any  record.  These 
speculations  are  not  based,  in  any  real  sense, 
upon  the  systematic  observation  of  natural 
phenomena.  Still,  as  they  appealed  to  human 
reason,  they  must  be  held  to  be  founded  upon 
experience,  or  at  least  not  to  be  consciously 
inconsistent  with  it:  All  the  oldest  cosmogonies 
regarded  water  as  the  fundamental  principle  of 
things :  from  Okeanos  sprang  the  gods  - —  them- 
selves deified  personifications  of  the  " elements" 
or  principles  of  which  the  world  was  made. 

In  the  course  of  time  this  doctrine  of  the 
origin  and  essential  nature  of  matter  came  to  be 
more  particularly  associated  with  the  name  of 
Thales  of  Miletus,  who  lived  six  centuries  before 
our  era,  and  who,  according  to  Tertullian,  is  to 
be  regarded  as  the  first  of  the  race  of  the  natural 
philosophers  —  that  is,  the  first  of  those  who 
made  it  their  business  to  inquire  after  natural 
causes  and  phenomena.  Thales  is  known  to 

19 


20  History  of  Chemistry 

have  passed  some  years  of  his  life  in  Egypt,  and 
to  have  been  instructed  in  science  by  the  priests 
of  Thebes  and  Memphis;  and  it  is  therefore 
possible  that  he  may  have  been  influenced 
by  the  Egyptian  teaching  in  the  formulation  of 
his  cosmological  theories. 

It  is  significant  of  the  tenacity  with  which  the 
mind  clings  to  dogma  and  reveres  authority  that 
the  teaching  of  Thales  should  have  survived 
through  the  space  of  twenty-four  centuries.  It 
can  be  shown  to  have  affected  the  course  of 
chemical  inquiry  down  to  the  close  of  the  eight- 
eenth century.  It  influenced  the  experimental 
labours  of  philosophers  so  diverse  in  character  as 
Van  Helmont,  Boyle,  Boerhaave,  Priestley,  and 
Lavoisier  —  all  of  whom  made  attempts  to 
prove  or  disprove  its  adequacy.  Van  Helmont, 
indeed,  was  one  of  the  most  strenuous  supporters 
of  the  doctrine  of  Thales,  and  sought  to  establish 
it  by  observations  which,  in  the  absence  of  all 
knowledge  of  the  true  nature  of  air  and  water, 
seemed  at  the  time  irrefutable.  Perhaps  the 
one  most  frequently  cited  is  his  observation  on 
the  growth  of  a  plant  which  apparently  had 
no  other  form  of  sustenance  than  water.  He 
describes  how  he  planted  a  willow  weighing  5  Ibs. 
in  200  Ibs.  of  earth  previously  dried  in  an  oven. 
The  plant  was  regularly  watered,  when  at  the 
end  of  five  years  it  was  found  to  weigh  169  Ibs. 
3  oz.,  whereas  the  earth,  after  redrying,  had  lost 


Chemical  Philosophy  21 

only  2  oz.  in  weight.  Hence,  164  Ibs.  of  woody 
matter,  leaves,  roots,  etc.,  had  been,  produced 
seemingly  from  water  alone.  More  than  a  cen- 
tury had  to  elapse  before  any  clue  to  the  true 
interpretation  of  Van  Helmont's  experiment 
was  gained.  It  was  first  furnished  by  the  obser- 
vations of  Ingenhousz  and  Priestley. 

Although  the  idea  of  a  primal  "  element"  or 
common  principle  is  to  be  found  in  every 
old-world  philosophical  system,  the  ancient 
philosophers  were  by  no  means  in  agreement  as 
to  its  character.  Anaximenes,  who  lived  circa 
500  B.C.,  taught  that  it  was  air,  Herakleitos  of 
Ephesus  that  it  was  fire,  and  Pherekides  that 
it  was  earth.  The  supposition  that  a  single 
primordial  principle  could  be  made  to  account 
for  all  forms  of  matter  and  all  the  phenomena 
and  manifestations  of  the  material  world  had 
its  difficulties.  Attempts  to  group  qualities  as 
principles,  and  to  construct  from  these  principles 
the  universe,  were  indeed  made  even  prior  to  the 
age  of  Thales.  It  was  a  comparatively  simple 
evolutionary  step  to  regard  these  principles  or 
1  'elements"  as  mutually  convertible.  Anaxi- 
menes' theory  of  the  formation  of  rain  was  an 
implicit  admission  of  such  convertibility.  This 
philosopher  taught  that  rain  came  by  the  con- 
densation of  clouds,  which  in  their  turn  were 
formed  by  the  condensation  of  air.  Everything 
conies  from  air  and  everything  returns  to  air. 


22  History  of  Chemistry 

That  water  might  be  converted  by  fire  into  air 
was  surmised  from  the  earliest  times.  Such  a 
supposition  naturally  sprung  from  the  circum- 
stance that  water  was  everywhere  recognised  to 
disappear  or  to  pass  into  the  air  under  the 
influence  of  fire  or  solar  heat.  The  supposition- 
had  grown  into  a  fixed  belief  in  the  Middle  Ages. 
Even  Priestley,  as  late  as  the  end  of  the  eight- 
eenth century,  imagined  for  a  time  that  he  had 
obtained  proof  of  such  a  mutual  conversion. 
The  possibility  of  the  transmutation  of  water 
into  earth  was  a  belief  current  through  twenty 
centuries,  and  was  only  definitely  and  finally 
disproved  by  Lavoisier  in  1770.  The  conception 
of  fire  as  the  primal  principle  has  its  germ  in  the 
fire-  or  sun-worship  of  the  Chaldeans,  Scythians, 
Persians,  Parsees,  and  Hindus,  and  it  is  not 
difficult  to  trace,  therefore,  how  heat  came  to 
be  regarded  either  as  antecedent  to,  or  as  asso- 
ciated with,  the  other  primal  principles.  Em- 
pedokles,  apparently,,  was  the  first  whose  name 
has  come  down  to  us  to  reproduce  the  definite 
conception  of  four  primal  elements  —  fire,  air, 
water,  and  earth.  These  he  regarded  as  distinct, 
and  incapable  of  being  transmuted,  but  as  form- 
ing all  varieties  of  matter  by  intermixture  in 
various  proportions.  These  principles  he  deified, 
Zeus  being  the  personification  of  the  element  of 
fire,  Here  of  air,  Nestis  of  water,  and  Aidoneous 
of  earth. 


Chemical  Philosophy  23 

The  doctrine  of  the  four  elements  was  also 
adopted  by  Plato  and  amplified  by  Aristotle, 
with  whose  name  indeed  it  is  commonly  asso- 
ciated. Aristotle,  the  greatest  scientific  thinker 
among  the  Greeks,  exercised  an  authority  almost 
supreme  in  Europe  during  nearly  twenty  cen- 
turies. His  influence  is  to  be  traced  throughout 
the  literature  of  chemistry  long  after  the  time 
of  Boyle.  It  may  be  detected  even  now.  Prob- 
ably few  who  write  chemical  memoirs  to-day, 
and  who  follow  the  time-honoured  practice  of 
prefacing  their  own  contributions  to  knowledge 
by  a  statement  of  what  is  already  known  on  the 
subject,  are  aware  that  in  so  doing  they  are 
obeying  the  injunctions  of  Aristotle.  His  theory 
of  the  nature  of  matter  is  contained  in  his  treat- 
ise on  Generation  and  Destruction.  It  mainly 
differed  from  that  of  Empedokles  in  regarding 
the  four  ''elements"  as  mutually  convertible. 
Each  '"element"  or  principle  was  regarded  as 
being  possessed  of  two  qualities,  one  of  which 
was  shared  by  another  element  or  principle. 

Thus:  Fire  is  hot  and  dry;  air  is  hot  and  wet; 
water  is  cold  and  wet;  earth  is  cold  and  dry. 

In  each  primal  "  element "  one  quality  prevails. 
Fire  is  more  hot  than  dry;  air  is  more  wet  than 
hot;  water  is  more  cold  than  wet;  earth  is  more 
dry  than  cold.  The  relative  proportion  and 
mutual  working  of  these  qualities  determined 
the  specific  character  of  the  "element."  Thus, 


24  History  of  Chemistry 

if  the  dryness  of  fire  is  overcome  by  the  moisture 
of  water,  air  is  produced;  if  the  heat  of  air  is 
overcome  by  the  coldness  of  earth,  water  is 
formed;  if  the  moisture  of  water  is  overcome 
by  the  dryness  of  fire,  earth  results.  Ancient 
chemical  literature  contains  many  illustrations 
or  diagrams  symbolising  the  convertibility  or 
mutual  relations  of  the  four  " elements." 

It  has  been  frequently  stated  that  the  influence 
of  the  Peripatetic  philosophy  has  been  inimical 
to  the  development  of  science.  But,  in  reality, 
the  founder  of  that  school,  a  descendant  of 
Esculapius,  and  undoubtedly  one  of  the  greatest 
and  most  enlightened  thinkers  of  antiquity,  was 
an  ideal  man  of  science.  This  is  abundantly 
evident  from  such  of  his  works  as  can  be  proved 
to  be  genuine.  Much  of  what  is  called  Aristote- 
lianism  is  entirely  foreign  to  the  spirit  of  the 
teaching  of  Aristotle.  The  Aristotelians  of  the 
Middle  Ages  were  mainly  dialecticians,  and 
almost  wholly  concerned  with  the  formulae  of 
syllogistic  inference,  and  without  real  sympathy 
with,  or  knowledge  of,  his  system.  Much,  too, 
that  was  attributed  to  him,  and  which  was 
venerated  accordingly,  is  undoubtedly  spurious. 
The  fame  of  the  Master  has  consequently  suffered 
at  the  hands  of  those  who,  calling  themselves 
Peripatetics,  were  in  no  proper  sense  followers  of 
his  method  or  interpreters  of  his  dogma.  Aris- 
totle affirmed  that  natural  science  can  only  be 


Chemical  Philosophy  25 

founded  upon  a  knowledge  of  facts,  and  facts 
can  only  be  ascertained  through  observation 
and  experiment.  He  illustrates  this  particularly 
by  a  reference  to  astronomy,  " which,"  he  says, 
"is  based  on  the  observation  of  astronomical 
phenomena,  and  it  is  the  case  with  every  branch 
of  science  or  art."  It  is  erroneous  and  unjust, 
therefore,  to  suppose  that  Aristotle's  philosophy, 
as  he  taught  it,  is  opposed  to  the  true  methods  of 
science. 

A  knowledge  of  Aristotle's  works  was  trans- 
ferred by  Byzantine  writers  to  Egypt;  and,  when 
that  land  was  overrun  by  the  Arabs  in  the 
seventh  century,  they  adopted  his  system, 
spreading  it  abroad  wherever  their  conquests 
extended.  In  the  eighth  century  they  carried 
it  into  Spain,  where  it  flourished  throughout 
their  occupation  of  that  country.  From  the 
ninth  to  the  eleventh  century  the  greater  part 
of  Europe  was  in  a  state  of  barbarism.  The 
Moslem  caliphate  in  Spain,  under  the  beneficent 
rule  of  Jusuf  and  Jaklib,  alone  preserved  science 
from  extinction.  Cordova,  Seville,  Grenada, 
and  Toledo  were  the  chief  seats  of  learning  in 
Western  Europe;  and  it  was  mainly  through 
"•the  perfect  and  most  glorious  physicist,"  the 
Moslem  Ibn-Roshd  —  better  known  as  Averroes 
—  (1126-1198),  that  Christian  scholiasts  like 
Roger  Bacon  acquired  their  knowledge  of  the 
philosophical  system  of  Aristotle,  and  mainly 


26  History  of  Chemistry 

through  the  Moslems  Geber  and  Avicenna  that 
they  gained  acquaintance  with  the  science  of 
the  East. 

The  conception  that  matter  is  made  up  of 
particles  or  atoms,  and  that  these  particles 
are  in  a  state  of  ceaseless  motion,  is  to  be 
met  with  in  Hindu  and  Phoenician  philosophy. 
It  was  taught  by  Anaxagoras,  Leukippos,  and 
Demokritos  to  the  Greeks,  and  by  Lucretius  to 
the  Romans.  Leukippos  and  Demokritos  ex- 
plained the  creation  of  the  world  as  due  solely  to 
physical  agencies  without  the  intervention  of  a 
creative  intelligence.  According  to  their  theo- 
ries, the  atoms  are  variable,  not  only  in  size, 
but  in  weight.  The  smallest  atoms  are  also 
the  lightest.  Atoms  are  impenetrable;  no  two 
atoms  can  simultaneously  occupy  the  same  place. 
The  collision  of  the  atoms  gives  them  an  oscilla- 
tory movement,  which  is  communicated  to  adja- 
cent atoms,  and  these,  in  their  turn,  transmit 
it  to  the  most  distant  ones.  Anaxagoras  taught 
that  every  atom  is  a  world  in  miniature,  and  that 
the  living  body  is  a  congeries  of  atoms  derived 
from  the  aliments  which  sustain  it.  Plants  are 
living  things,  endowed  like  animals  with  res- 
piratory functions,  and,  like  them,  atomicaliy 
constituted.  This  philosopher  was  so  far  in 
advance  of  his  age  that  his  countrymen  accused 
him  of  sacrilege,  and  he  only  escaped  death  by 
flight.  Further,  the  assumption  that  these  atoms 


Chemical  Philosophy  27 

exert  mutual  attractions  and  repulsions  is  prob- 
ably as  old  as  thp  fundamental  conception  itself. 
At  least,  so  far  as  can  be  traced,  the  conceptions 
of  atoms  and  atomic  motion  are  indissolubly 
connected.  This  is  not  the  place  to  develop  the 
subsequent  history  of  the  doctrine  of  the  atom, 
nor  need  we  now  concern  ourselves  with  the  old 
metaphysical  quibble  of  its  divisibility  or  indivisi- 
bility. It  may  be,  as  Lucretius  said,  that  the 
original  atom  is  very  far  down.  It  may  be  that 
the  physical  atom  is  something  which  is  not 
divided,  not  something  that  cannot  be  divided. 
This  theory,  dimly  perceived  in  the  mists  of  anti- 
quity, has  grown  and  strengthened  with  the  ages, 
and  in  its  modern  application  to  the  facts  of 
chemistry  has  acquired  a  precision  and  harmony 
unimagined  even  by  the  poets  and  thinkers  of 
old.  We  shall  see  later  how  the  whole  course  of 
the  science  has  been  controlled,  illumined,  and 
vivified  by  it.  It  is  not  too  much  to  say  that 
the  chemistry  of  to-day  is  one  vast  elaboration 
of  this  primeval  doctrine. 


CHAPTER    III 
ALCHEMY 

A  LTHOUGH  the  intellectual  tendencies  of  the 
Hellenic  mind  were  hardly  calculated  to 
favour  the  development  of  chemistry  as  a  science, 
the  speculations  of  the  Greeks  concerning  the 
essential  nature  of  matter  and  the  mutual  con- 
vertibility of  the  "elements"  led  incidentally  to 
an  extension  of  the  art  of  operative  chemistry. 
This  extension  resulted  from  attempts  to  realise 
what  was  the  logical  outcome  of  the  teaching  of 
their  philosophers  —  viz.,  the  possibility  of  the 
transmutation  of  metals.  The  idea  of  transmu- 
tation has  its  germ  in  the  oldest  systems  of 
philosophy.  It  was  a  plausible  doctrine,  not 
wholly  unsupported  by  the  phenomena  of  the 
organic  world;  and  it  naturally  commended 
itself  to  men  who  were  only  too  prone  to  adopt 
what  their  cupidity  and  love  of  wealth  predis- 
posed them  to  believe. 

It  has  been  assumed  that  alchemy  at  no  time 
in  its  history  had  the  slightest  claim  to  a  phil- 
osophical foundation,  but  that  its  professors  and 
adepts,  even  at  the  outset,  consciously  traded 
on  the  credulity  and  greed  of  their  dupes.  Much 
28 


Alchemy  29 

may  be  urged  against  such  a  partial  view.  The 
supposition  is  not  consistent  with  history  or 
with  evolutional  tendencies.  It  may  be,  as 
Davy  once  said,  that  "  analogy  is  the  fruitful 
parent  of  error;"  but  the  idea  that  metals  could 
be  modified  -—could  even  be  changed  one  into 
the  other  —  seemed  to  find  support  in  innumer- 
able chemical  phenomena  well  known  but 
imperfectly  understood.  The  fact  that  alchemy. 
-  that  is  the  profession  of  making  gold  from 
other  metals  —  came  to  be*  practised  by  rogues  is 
no  proof  that  it  never  had,  and  never  could  have 
had,  a  philosophical  basis. 

The  changes  which  substances  experience 
under  the  influence  of  fire,  air,  and  water,  or  as 
the  result  of  their  action  on  each  other,  are 
frequently  so  profound  that  even  the  most  super- 
ficial of  the  early  observers  of  chemical  processes 
could  not  fail  to  be  impressed  by  them.  Many 
of  these  changes  are,  in  fact,  far  more  striking  as 
regards  alteration  in  outward  characters  —  such 
as  colour,  lustre,  density,  etc.  —  than  are  the 
differences  between  individual  metals;  say,  be- 
tween lead  and  tin,  or  between  tin  and  silver, 
or  between  brass  and  gold.  That  copper  ores,  by 
appropriate  treatment  with  other  ores,  or  that 
copper  itself  by  the  addition  of  another  metal, 
could  be  made  to  furnish  a  metallic-looking 
substance  having  certain  of  the  attributes  of 
gold  was  known  to  the  earliest  workers  in  metals. 


30  History  of  Chemistry 

What  is  thought  to  be  the  oldest  chemical 
treatise  in  existence  is  a  papyrus  in  the  possession 
of  the  University  of  Ley  den.  It  consists  of  a 
number  of  receipts  for  the  working  of  metals  and 
alloys,  and  describes  methods  of  imitating  and 
falsifying  the  noble  metals.  It  explains  how, 
by  means  of  arsenic,  a  white  colour  may  be 
given  to  certain  metals,  and  how,  by  the  addition 
of  cadmia,  copper  acquires  the  colour  of  gold. 
The  same  papyrus  describes  a  method  of  black- 
ening metals  by  the  Tise  of  preparations  of  sul- 
phur. The  limited  knowledge  of  chemical 
phenomena  and  of  chemical  processes  which 
these  early  workers  necessarily  possessed,  so  far 
from  precluding  a  belief  in  the  possibility  of 
transmutation,  actually  encouraged  it.  As  no- 
thing was  known  of  the  true  nature  of  brass 
or  of  its  exact  relation  to  copper,  it  was  not 
unreasonable  to  suppose  that,  if  this  substance 
could  be  made  to  acquire  some  of  the  attributes 
of  gold  by  '  a  process  essentially  chemical, 
processes  of  a  like  nature  might  cause  it  to 
acquire,  if  not  all,  at  least  so  many  of  them  as 
to  enable  it  to  pass  for  gold  of  greater  or  less 
fineness.  To  them,  as  to  us,  perfection  was, 
in  technical  practice,  a  question  of  degree:  the 
very  language  of  the  metallurgists  of  old  was 
in  this  respect  nowise  different  from  that  of  the 
metallurgists  of  to-day. 

It  is  not  necessary  to  suppose  that  these  early 


Alchemy  31 

attempts  were  deliberately  and  consciously 
fraudulent,  like  those  of  coiners  who  knowingly 
seek  to  make  an  alloy  of  lead  and  tin  simulate 
silver.  The  first  alchemists  sought  in  good  faith 
to  make  something  which  should  be  of  the  true 
nature  and  essence  of  gold  as  they  conceived  it 
to  be.  In  fact,  the  idea  of  transmutation  had 
a  rational  foundation  in  a  theory  of  the  intrinsic 
nature  of  metals  which  may  be  looked  upon  as  a 
development  of  the  ancient  beliefs  concerning 
the  essential  nature  of  all  forms  of  matter. 

Just  as  the  Aristotelian  " elements"  were 
qualities  which,  according  to  their  degree,  deter- 
mined the  nature  of  substances,  so,  in  like  man- 
ner, the  specific  character  of  a  metal  depended 
upon  the  relative  proportion  of  its  " sulphur" 
and  "mercury."  These  terms  had  no  certain 
reference  to  what  we  to-day  understand  by 
sulphur  and  mercury.  They  denoted  simply 
qualities.  The  essence  or  " element"  of  mer- 
cury conferred  lustre,  malleability,  ductility,  and 
fusibility,  or,  speaking  generally,  the  properties 
which  we  connote  as  metallic;  while  to  the 
essence  or  " element"  of  sulphur  was  to  be  at- 
tributed the  combustibility  —  or,  speaking 
generally,  the  alterability  —  of  the  metal  by  fire. 
By  modifying  the  relative  proportion  of  these 
constituent  elements,  or  by  purifying  them 
from  extraneous  substances  by  the  operations 
of  chemistry,  it  was  conceived  that  the  several 


32  History  of  Chemistry 

metals  could  be  changed  one  into  the  other.  To 
effect  this  ^purification  it  was  necessary  to  add 
various  preparations  known  as  "medicines," 
chief  among  which  was  the  Great  Elixir,  or 
Magisterium,  or  the  Philosopher's  Stone,  by 
which  the  final  transformation  into  the  noblest 
of  the  metals  could  alone  be  achieved. 

The  Arabic  words  kimya  and  iksir  were  origi- 
nally synonymous  and  each  was  used  to  denote 
the  agent  by  which  the  baser  metals  could  be 
transmuted  into  silver  and  gold.  Ultimately 
the  former  term  became  restricted  to  indicate 
the  art  of  transmutation  (alchemy),  whereas 
ikslr,  or  al-iksir,  continued  to  denote  the  me- 
dium by  which  the  transmutation  was  effected. 
By  later  writers  the  term  was  used  to  indicate 
a  liquid  preparation  —  the  quintessence  of  the 
philosophers  —  whence  we  have  the  word  elixir, 
which  always  means  a  liquid. 

The  alchemistic  theory  of  the  compound  na- 
ture and  mutual  relations  of  the  metals  is  usu- 
ally ascribed  to  Geber;  but,  although  he  adopted 
it,  he  distinctly  states  that  it  did  not  .originate 
with  him,  but  that  he  found  it  in  the  writings 
of  his  predecessors. 

The  idea  of  the  stone,  the  philosophical  powder, 
the  grand  magisterium,  the  elixir,  the  tincture, 
the  quintessence  —  by  all  of  which  terms  the 
transmuting  medium  is  known  in  the  litera- 
ture of  alchemy  —  is  probably  connected  with 


Alchemy     .  33 

another  conception  respecting  the  origin  of 
metals  which  can  be  traced  to  very  early  times 
and  was  prevalent  throughout  the  Middle  Ages. 
It  was  supposed  of  old  that  metals  were  generated 
within  the  earth,  as  animals  and  plants  were 
generated  on  its  surface,  and  that  something 
akin  to  a  seed,  or  semen,  was  needed  to  initiate 
their  formation.  The  great  problem  of  alchemy 
was  to  discover  this  fecundating  substance,  as 
upon  it  depended  the  genesis  of  the  perfect 
metal.  This  idea  of  the  conception  of  metals 
runs  through  the  literature  of  alchemy.  It  ex- 
plains many  allusions  and  much  of  the  termi- 
nology of  its  writers.  For  example,  the  furnace 
in  which  the  alchemist  makes  his  projection  is 
constantly  spoken  of  as  the  philosophical  egg. 

It  is  impossible  to  say  with  certainty  when 
and  where  the  art  of  alchemy  originated.  There 
is  no  evidence  that  it  has  the  antiquity  which 
certain  of  its  adepts  claimed  for  it.  Oleus 
Borrichius  referred  it  to  the  time  of  Tubal-cain. 
The  earliest  writers  on  alchemy  were  probably 
Byzantine  ecclesiastics,  some  of  whom  professed 
to  ascribe  the  art  to  Egypt,  and  eventually  to 
the  mythological  d^ity  Hermes,  whose  associa- 
tion with  chemistry  in  such  terms  as  "the  her- 
metic art,"  " hermetically  sealed,"  etc.,  is  thus 
explained. 

This  much  is  established  --  that  at  some 
period  prior  to  the  tenth  century  there  arose  a 


34  History  of  Chemistry 

special  class  of  operative  chemists,  for  the  most 
part  more  learned  in  the  knowledge  of  chemical 
phenomena  in  general,  and  more  skilled  in  chem- 
ical manipulation,  than  the  craftsmen  and  arti- 
sans engaged  in  the  manufacture  of  technical 
products.  They  devoted  themselves  to  search- 
ing for  methods  whereby  the  common  and  baser 
metals  might  be  converted  into  silver  and  gold. 
The  first  known  definition  of  chemistry  relates 
to  the  aim  and  operations  of  this  special  class. 
It  occurs  in  the  lexicon  of  Suidas,  a  Greek  writer 
of  the  eleventh  century,  who  defines  chemistry, 
%T)JJ.COL  as  the  preparation  of  silver  and  gold.  At- 
tempts at  the  artificial  preparation  of  the  noble 
metals  probably  originated  with  the  Arabians, 
who  followed  the  Egyptians  and  the  Greeks  in 
the  cultivation  of  chemical  pursuits. 

Neither  Hesiod  nor  Homer  makes  mention  of 
the  art  of  producing  gold  from  any  other  metal, 
or  speaks  of  the  universal  medicine.  Nor  are  they 
referred  to  by  Aristotle  or  by  his  pupil  Theophras- 
tus.  Pliny  nowhere  speaks  of  the  philosopher's 
stone,  although  he  tells  the  story  of  Caligula, 
who,  tempted  by  his  avarice,  sought  to  make 
gold  from  orpiment  (auripigmentum)  by  distil- 
lation. "The  result  was  that  he  did  indeed  ob- 
tain both,  and  of  the  finest  kind;  but  in  so  small 
quantity,  and  with  so  much  labour  and  appara- 
tus, that,  the  profit  not  countervailing  the  ex- 
pense, he  desisted." 


Alchemy  35 

According  to  Boerhaave,  the  first  author  who 
mentions  al-chemia  is  Julius  Firmicus  Maternus, 
who  lived  under  Constantine  the  Great,  and  who, 
in  his  Mathesis,  c.  15,  speaking  of  the  influences 
of  the  heavenly  bodies,  affirms  "that,  if  the 
moon  be  in  the  house  of  Saturn  when  a  child  is 
born,  he  shall  be  skilled  in  alchemy.  " 

The  first  writer  who  mentions  the  possibility 
of  transmuting  metals  would  appear  to  be  a 
Greek  divine  called  ^Eneas  Garaeus,  who  lived 
towards  the  close  of  the  fifth  century,  and  who 
wrote  a  commentary  on  Theophrastus.  He  was 
followed  by  Anastatius  the  Sinaite,  Syncellus, 
Stephanus,  Olimpiodorus;  and,  says  Boerhaave, 
"a  crowd  of  no  less  than  fifty  more,  all  Greeks, 
and  most  or  all  of  them  monks."  "The  art 
seemed  now  confined  to  the  Greeks,  and  among 
them  few  wrote  but  the  religious,  who  from 
their  great  laziness  and  solitary  way  of  life 
were  led  into  vain,  enthusiastical  speculations, 
to  the  great  disservice  and  adulteration  of  the 
art.  .  .  They  all  wrote  in  the  natural  style  of 
the  Schoolmen,  full  of  jargon,  grimace,  and  ob- 
scurity. " 

Experimental  alchemy,  as  distinguished  from 
industrial  chemistry,  may,  as  already  stated,  be 
said  to  have  originated  with  the  Arabians.  At 
first,  alchemy  was  regarded  as  a  branch  of  the 
art  of  healing,  and  its  professors  were  invariably 
physicians  who  occupied  themselves  with  the 


36  History  of  Chemistry 

preparation  of  chemical  medicines.  In  fact,  in 
the  beginning  its  true  aim  was  regarded  as  that 
which  Paracelsus  and  the  school  of  iatro-chem- 
ists  subsequently  defined  it  to  be.  Under  the 
rule  of  the  Caliphs  the  study  of  chemistry  made 
considerable  progress,  and  its  literature  twas 
greatly  augmented.  The  most  notable  name  in 
the  history  of  chemistry  during  the  eighth 
century  was  Abu-Moussah-Dschabir-Al-Sufi  — 
otherwise  Geber — (born  702,  died  765),  who 
is  stated  to  have  been  either  a  native  of  Meso- 
potamia, or  a  Greek  and  a  Christian,  who  after- 
wards embraced  Mahometanism,  went  to  Asia, 
and  acquired  a  knowledge  of  Arabic.  Accord- 
ing to  Leo  Africanus,  a  Greek  who  wrote  of  the 
antiquity  of  the  Arabs,  Geber's  book  was  origi- 
nally written  in  Greek  and  translated  thence  into 
Arabic,  and  he  was  not  known  by  the  name  Geber, 
which  signifies  a  great  man  or  a  prince,  till  after  this 
version.  Latin  translations  of  what  purported 
to  be  his  works  were  first  published  in  the  early 
part  of  the  sixteenth  century,  and  an  English 
rendering  appeared  in  1678.  According  to  this 
it  would  seem  that  Geber  regarded  all  the  metals 
as  compounds  of  " sulphur"  and  "mercury," 
the  differences  between  them  depending  upon  the 
relative  proportion  and  degree  of  purity  of  these 
constituents.  He  is  said  to  have  distinguished 
them  by  the  astrological  names  of  the  planets: 
thus  gold  became  Sol,  silver  Luna,  copper  Venus, 


Alchemy  37 

. 

iron  Mars,  tin  Jupiter,  and  lead  Saturn.  That 
an  occult  connection  of  the  metals  with  the  stars 
existed  was  part  of  the  creed  of  alchemy,  and 
the  influence  of  that  belief  is  still  traceable  in 
chemical,  and  especially  in  pharmaceutical, 
literature;  as,  for  example,  in  such  terms  as 
Lunar  caustic,  Martian  preparations,  Saturnine 
solutions,  etc. 

It  has  been  held  that  the  idea  of  a  universal 
medicine  had  its  origin  with  Geber.  But  this 
may  be  due  to  a  misreading  of  his  words,  which 
in  reality  may  have  reference  to  the  transmuta- 
tion of  metals.  He  tells  of  a  medicine  which 
cures  all  lepers.  But  this  may  be  nothing  but 
allegory.  By  man  is  probably  meant  gold,  and 
by  lepers  the  other  metals;  and  the  medicine  is 
the  universal  solvent  or  agent  which  transmutes. 
Alchemistic  literature  is  full  of  allegories  of  this 
character.  Berthelot  has  shown  that  in  reality 
there  were  two  Gebers  —  one  who  is  generally 
considered  to  be  of  Arab  origin,  and  another 
whose  identity  is  not  established,  but  who  was 
probably  a  Western  European  who  appears  to 
have  lived  about  the  year  I300.1 

Other  notable  names  in  the  history  of  Ara- 

1  There  is  very  little  doubt  that  the  work  of  "Philel- 
etha,"  which  professed  to  be  taken  from  an  "  Uhralten 
MS."  preserved  in  the  Vatican  Library,  entitled  Geberi 
des  Koniges  der  Araber,  and  published  by  Hieron. 
Philipp.  Nitschel,  Frankfurth  and  Leipzig,  in  1710,  is 
spurious. 


38  •  History  of  Chemistry 

biah  alchemy  are  Rhazes,  or  Abu  Bakr 
Mohammed  ibn  Zakaraya  el-Razi,  who  lived 
circa  925,  and  Avicenna,  or  in  Arabic  Abu  All 
el-Hosein  ibn-Abdallah  ibn-Sina,  born  980, 
died  1037.  The  former,  a  Persian,  practised 
medicine  at  Baghdad  as  a  follower  of  Galen  and 
Hippocrates.  The  latter,  one  of  the  most 
eminent  of  Moslem  physicians  and  a  voluminous 
writer,  was  a  native  of  Bokhara.  He  is  mainly 
known  in  the  history  of  science  by  his  Canon  of 
Medicine,  in  which  he  describes  the  composition 
and  preparation  of  remedies.  He  wrote  at 
least  one  treatise  on  alchemy,  but  others  attrib- 
uted to  him  are  probably  apocryphal.  Of  his 
Pkilosopkia  Orientalis,  mentioned  by  Roger 
Bacon  and  Averroes,  no  trace  remains. 

Although  it  is  reasonably  certain  that  the 
alchemists  of  the  time  of  Geber  and  of  his  suc- 
cessors had  a  considerable  acquaintance  with 
manipulative  chemistry,  there  were  so  many 
impudent  literary  forgeries  during  the  alchemical 
period  that  the  precise  extent  of  the  knowledge 
possessed  by  the  early  chemists  must  always 
remain  uncertain. 

A  number  of  the  ordinary  chemical  processes, 
such  as  distillation,  sublimation,  calcination, 
filtration,  appear  to  have  been  known  to,  and 
to  have  been  commonly  practised  by,  the  Ara- 
bian chemists;  and  many  saline  substances,  such 
as  carbonate  of  soda,  pearlash,  sal-ammoniac, 


Alchemy  39 

alum,  copperas,  borax,  silver  nitrate,  cinnabar, 
and  corrosive  sublimate,  were  prepared  by  them. 
They  seem  to  have  known  of  certain  of  the 
mineral  acids,  and  were  familiar  with  the  solvent 
properties  of  aqua  regia. 

An  examination  of  the  literature  of  alchemy 
serves  to  show  how  its  principles  and  tenets 
developed.  The  philosopher's  stone  is  first 
heard  of  in  the  twelfth  century.  Prior  to  that 
period  the  greater  number  of  the  Greek  and 
Arabian  writers  contented  themselves  with 
affirming  the  fact  of  transmutation,  without 
indicating  how  it  might  be  accomplished.  The 
universal  medicine  and  the  elixir  of  life  were  the 
products  of  a  later  age;  no  mention  of  them  is 
known  before  the  thirteenth  century. 

Alchemy  flourished  vigorously  during  the 
Middle  Ages,  and  lingered  on  even  until  the 
early  part  of  the  nineteenth  century.  Its  his- 
tory is  simply  a  long  chapter  in  the  history  of 
human  credulity.  For  the  most  part  it  is  a 
record  of  self-deception,  imposture,  and  fraud. 
It  produced  an  abundant  literature,  mainly  the 
work  of  ecclesiastics,  between  the  seventh  and 
fourteenth  centuries ;  but  as  regards  the  artificial 
preparation  of  the  noble  metals  or  the  discovery 
of  the  universal  medicine  or  the  elixir  of  life  it 
was  barren  of  result. 

Although  no  clear  line  of  demarcation  is  possi- 
ble, it  may  be  convenient,  in  dealing  with  the 


40  History  of  Chemistry 

personal  history  of  alchemy,  to  divide  it  into  the 
two  periods  before  and  after  Paracelsus,  since 
under  his  inspiration  and  example  alchemy 
underwent  a  great  development  as  regards  its 
professed  objects.  These  eventually  became  so 
extravagant  that,  wide  as  are  the  limits  of  human 
credulity,  its  pretensions  gradually  brought  it 
into  disrepute,  and  it  fell  by  the  weight  of  its  own 
absurdities. 

One  of  the  most  reputable  of  the  early  West- 
ern alchemists  was  Albert  Groot,  or  Albertus 
Magnus,  born  at  Lauingen  in  1193.  He  was  a 
Dominican  monk,  who  became  Bishop  of  Regens- 
burg,  but,  resigning  his  bishopric,  retired  to  a 
convent  at  Cologne,  where  he  devoted  himself 
to  science  until  his  death  in  1282.  He  is  credited 
with  having  written  a  number  of  chemical 
.tracts,  for  the  most  part  in  clear  and  intelligible 
language,  which  is  more  than  can  be  said  of  the 
greater  portion  of  alchemistical  literature.  He 
gives  an  account  of  the  origin  and  main  proper- 
ties of  the  chemical  substances  known  in  his 
time,  and  describes  the  apparatus  and  processes 
used  by  chemists,  such  as  the  water-bath,  alem- 
bics, aludels,  and  cupels.  He  speaks  of  cream 
of  tartar,  alum  and  caustic  alkali,  red  lead, 
liver  of  sulphur  and  arsenic,  green  vitriol  and 
iron  pyrites. 

Contemporaneously  with  him  was  Roger 
Bacon,  Doctor  Mirabilis,  one  of  the  most  erudite 


Alchemy  41 

men  of  his  age,  who  was  born  near  Ilchester  in 
Somerset  in  1214,  and,  after  studying  at  Oxford, 
became  a  friar,  occupied  himself  in  philosophical 
pursuits,  and  wrote  numerous  tracts  on  alchemy. 
He  describes  what  was  probably  gunpowder, 
but  there  is  no  certain  proof  that  he  invented  it. 
In  his  De  Secretis  Artis  et  Nature?,  written  before 
1249,  ne  gives  instructions  for  refining  saltpetre, 
and  in  an  anagram  which  Colonel  Hime,  in  his 
Gunpowder  and  Ammunition,  has  interpreted, 
he  states  that  a  mixture  "  which  will  produce  a 
thundering  noise  and  a  bright  flash"  may  be 
made  by  taking  "  7  parts  of  saltpetre,  5  of  young 
hazelwood,  and  5  of  sulphur.  "  He  died  in  1285. 
Raymund  Lully,  a  friend  and  scholar  of 
Bacon,  was  born  in  Majorca  in  1225  (others  say 
1235),  and  was  buried  there  in  1315.  A  member 
of  the  Order  of  Minorites,  he  had  a  great  reputa- 
tion as  an  alchemist ;  and  a  number  of  books  on 
alchemy  and  chemical  processes  are  ascribed  to 
him.  He  described  modes  of  obtaining  nitric 
acid  and  aqua  regia,  and  studied  their  action 
upon  metals.  He  obtained  alcohol  by  distilla- 
tion, and  knew  how  to  dehydrate  it  by  the  aid 
of  carbonate  of  potash,  which  he  obtained  by 
calcining  cream  of  tartar.  He  prepared  various 
tinctures  and  essential  oils,  and  a  number  of 
metallic  compounds,  such  as  red  and  white 
precipitate.  To  him  is  usually  ascribed  the  first 
idea  of  a  universal  medicine, 


42  History  of  Chemistry 

There  is  some  difficulty  in  believing  that  all 
that  is  ascribed  to  Lully  was  actually  the  work 
of  his  age,  for  it  would  appear  to  have  been  a 
common  practice  with  the  disciples  and  followers 
of  a  notable  scholar  to  usher  in  their  perform- 
ances under  their  master's  name  —  a  practice 
not  unknown  in  later  days.  "  So  full  are  they  of 
the  experiments  and  observations  which  occur  in 
our  later  writers  that  either  the  books  must  be 
suppositious,  or  the  ancient  chemists  must  have 
been  acquainted  with  a  world  of  things  which 
pass  for  the  discoveries  of  modern  practice" 
(Boerhaave).  The  story  is  that  Lully  plunged 
into  the  study  of  chemistry  from  the  desire  to 
cure  a  maiden  of  a  cancered  breast,  and  that  he 
was  stoned  to  death  in  Africa,  whither  he  had 
journeyed  as  a  missionary.  It  has  been  further 
alleged  that  at  one  period  of  his  life  he  made  gold 
in  the  Tower  of  London  by  the  King's  order,  and 
that  he  offered  Edward  III.  a  supply  of  six 
millions  to  make  war  against  the  infidels.  As 
Boerhaave  drily  remarks,  "the  history  of  this 
eminent  adept  is  very  much  imbroiled. " 

Arnoldus  Villanovanus,  or  Arnaud  de  Ville- 
neuve,  a  Frenchman,  is  said  to  have  been  born 
in  1240,  and  to  have  practised  medicine  in 
Barcelona,  where  he  incurred  the  enmity  of  the 
Church  by  reason  of  his  heretical  opinions,  and 
was  obliged  to  leave  Spain.  He  led  a  wandering 
life,  eventually  settling  in  Sicily,  under  the 


Alchemy  43 

protection  of  Frederick  II.,  and  acquired  a  great 
reputation  as  a  physician.  Summoned  thence 
by  Clement  V.,  who  lay  sick  at  Avignon,  he 
lost  his  life  by  shipwreck  in  1313. 

Johannes  de  Rupecissa,  or  Jean  de  Raque- 
taillade,  a  Franciscan  friar  who  lived  from 
about  the  middle  to  the  end  of  the  fourteenth 
century,  wrote  a  number  of  treatises  on  alchemy, 
and  described  methods  of  making  calomel  and 
corrosive  sublimate.  He  was  accused  of  the 
practice  of  magic,  and,  by  order  of  Innocent  VI., 
was  thrown  into  prison,  where  he  died.  He  was 
buried  at  Villefranche. 

George  Ripley,  an  Englishman,  Canon  of 
Bridlington,  practised  alchemy  during  the  second 
half  of  the  fifteenth  century.  He  spent  some 
time  in  Italy  in  the  service  of  Innocent  VIII. 
On  his  return  to  England  he  became  a  Carmelite, 
and  died  in  1490.  Like  Bacon,  he  was  charged 
with  magic.  According  to  Mundanus,  he  fol- 
lowe,d  alchemy  with  such  success  that  he  was  able 
to  advance  to  the  knights  of  St.  John  of  Jerusalem 
large  amounts  of  gold  for  the  defence  of  the  Isle 
of  Rhodes  against  the  Turks. 

One  of  the  most  important  names  in  connec- 
tion with  the  history  of  alchemy  is  that  of  Basil 
Valentine.  Of  his  personal  history  nothing  is 
known.  He  was  supposed  to  be  a  Benedictine 
monk  who  lived  in  Saxony  during  the  latter  half 
of  the  fifteenth  century;  but  there  are  grounds 


44  History  of  Chemistry 

for  the  belief  that  the  numerous  writings  attrib- 
uted to  hhn  are  in  reality  the  work  of  various 
hands.  The  attempt  made  by  Maximilian  I. 
to  discover  the  identity  of  the  author  was  un- 
availing, nor  have  subsequent  inquiries  had  any 
better  result.  The  collection  of  books  bearing 
his  name,  first  published  in  the  beginning  of  the 
seventeenth  century,  reveals  quite  a  remarkable 
number  of  chemical  facts  up  to  that  time  not 
generally  known.  The  most  important  of  these 
relate  to  antimony  and  its  preparations,  such  as 
butter  of  antimony,  powder  of  algaroth,  oxide  of 
antimony,  etc.  He  seems  to  have  known  of 
arsenic,  zinc,  bismuth,  and  manganese.  He 
described  a  number  of  mercurial  preparations, 
and  many  of  the  salts  of  lead  were  known  to  him. 
He  mentions  fulminating  gold,  and  was  aware 
that  iron  could  be  coated  with  copper  by  immer- 
sion in  a  solution  of  blue  vitriol.  He  knew  of 
green  vitriol  and  the  double  chloride  of  iron  and 
ammonium,  and  gave  the  modes  of  making  a 
considerable  number  of  other  metallic  salts, 
such  as  the  sal  armoniacum,  which  we  now 
know  as  sal  ammoniac.  He  also  appears  to 
have  prepared  ether  and  the  chloride  and  nitrate 
of  ethyl. 

There  is  reason  to  believe,  as  stated  already, 
that  many  of  the  published  works  ascribed  to 
these  learned  men  are  the  work  of  obscure  indi- 
viduals who  traded  on  their  fame.  What  may 


Alchemy  45 

with  certainty  be  credited  to  them  serves  to 
show  that  their  theoretical  opinions  had  much 
in  common.  They  all  regarded  the  transmuta- 
tion of  metals  and  the  existence  of  the  philoso- 
pher's stone  as  facts  which  could  not  be  contro- 
verted. They  followed  Geber  in  assuming  that 
all  the  metals  were  essentially  compound  in 
their  nature,  and  consisted  of  the  essence  or 
"element"  of  mercury,  united  with  different 
proportions  of  the  essence  or  "element"  of 
sulphur. 

The  alchemists  were  the  professional  chemists 
of  their  time,  and  many  of  them  were  practising 
physicians.  Indeed,  professional  chemistry  may 
be  said  to  have  originated  out  of  the  practice  of 
physic.  As  the  number  of  chemical  products 
increased  and  their  value  in  therapeutics  became 
more  and  more  appreciated,  there  arose  .another 
school  of  alchemists,  whose  energies  were  de- 
voted, not  to  the  transmutation  of  metals  — 
which,  however  plausible  as  a  belief,  seemed 
hopeless  of  achievement  —  but  to  the  more 
immediate  practical  benefits  which  it  was  recog- 
'nised  must  follow  from  the  closer  association  of 
chemistry  and  medicine.  This  school  came  to  be 
known  as  the  iatro-chemists.  As  their  doctrines 
exercised  a  great  influence  upon  the  development 
of  chemistry,  it  will  be  desirable  to  treat  of  them 
and  their  professors  in  a  special  chapter. 


CHAPTER    IV 
THE  PHILOSOPHER'S  STONE 

F^vURING  the  fourteenth,  fifteenth,  and  six- 
*~^  teenth  centuries  the  cult  of  alchemy  attained 
to  the  dignity  of  a  religion.  Belief  in  transmuta- 
tion and  in  the  virtues  and  powers  of  the  philoso- 
pher's stone,  in  the  universal  medicine,  the 
alkahest,  and  the  elixir  of  life,  formed  its  articles 
of  faith.  The  position  it  acquired  was  due  to 
some  extent  to  the  attitude  towards  it  of  the 
Romish  Church.  Many  reputable  bishops  and 
fathers  were  professed  alchemists;  and  chemical 
laboratories,  as  in  the  Egyptian  temples,  were  to 
be  found  in  monasteries  throughout  Christendom. 
Pope  John  XXII.,  who  had  a  laboratory  in  his 
palace  at  Avignon,  is  the  reputed  author  of  a 
work,  Ars  Transmutatoria,  published  in  1557. 
But  to  a  still  larger  extent  it  was  due  to  the  fact 
that  alchemy  appealed  to  some  of  the  strongest 
of  human  motives  —  the  wish  for  health,  the 
fear  of  death,  and  the  love  of  wealth.  It  was  a 
cunningly  devised  system,  which  exploited  the 
foibles  and  frailties  of  human  nature.  The 
policy  of  the  Church,  however,  it  should  be  said, 
was  not  consistently  and  uniformly  favourable  to 
alchemy.  Its  practices  occasionally  came  under 
46 


The  Philosopher's  Stone  47 

the  papal  ban,  although  at  times,  to  suit  the 
exigencies  of  Christian  princes,  the  interdict  was 
removed.  Theosophy  and  mysticism  were  first 
imported  into  alchemy,  not  by  Arabs,  but  by 
Christian  workers.  The  intimate  association  of 
religion  with  alchemy  during  the  Middle  Ages  is 
obvious  in  the  writings  of  Lully,.  Albertus 
Magnus,  Arnaud  de  Villeneuve,  Basil  Valentine, 
and  other  ecclesiastics.  Invocations  to  divine 
authority  are  freely  scattered  over  their  pages. 
Even  the  lay  alchemist  professed  to  rule  his  life 
and  conduct  by  the  example  and  precepts  of  the 
good  Bishop  of  Regensburg.  He  was  directed 
to  be  patient,  assiduous,  and  persevering;  dis- 
creet and  silent;  to  work  alone;  to  shun  the 
favour  of  princes  and  nobles,  and  to  ask  the 
divine  blessing  on  each  operation  of  trituration, 
sublimation,  fixation,  calcination,  solution,  dis- 
tillation, and  coagulation. 

Although  alchemy,  at  least  in  its  decadent 
days,  lived  for  the  most  part  by  its  appeal  to 
some  of  the  lowest  instincts  of  mankind,  and  is 
only  worth  notice  as  a  transient  phase  in  the 
history  of  science,  a  few  details  concerning  the 
tenets  and  practices  of  its  professors  may  be  of 
interest  to  the  curious  reader.  And  first  as  re- 
gards the  nature  of  the  philosopher's  stone  — 
the  grand  magistery,  the  quintessence.  Many 
alchemists  professed  to  have  seen  and  handled 
it.  It  is  usually  described  as  a  red  powder. 


48  History  of  Chemistry 

Lully  mentions  it  under  the  name  of  Carbuncu- 
lus.  Paracelsus  says*  that  it  was  like  a  ruby, 
transparent  and  brittle  as  glass;  Berigard  de 
Pisa  that  it  was  of  the  colour  of  a  wild  poppy, 
with  the  smell  of  heated  sea  salt;  Van  Helmont 
that  it  was  like  saffron,  with  the  lustre  of  glass. 
Helvetius  describes  it  as  of  the  colour  of  sulphur. 
Lastly,  an  unknown  writer,  under  the  pseudonym 
of  "  Kalid,  "  says  that  it  may  be  of  any  colour  — 
white,  red,  yellow,  sky-blue,  or  green.  As  the 
substance  was  wholly  mythical,  a  certain  lati- 
tude of  description  may  reasonably  be  expected. 
Some  of  the  alchemists  were  of  opinion  that  the 
magistery  was  of  two  kinds  —  the  first,  the 
grand  magistery,  needed  for  the  production  of 
gold;  the  second,  the  small  magistery,  only  capa- 
ble of  ennobling  a  metal  as  far  as  the  stage  of 
silver.  Then,  as  to  the  amounts  required  to 
effect  a  transmutation,  accounts  are  equally 
discrepant.  Arnaud  de  Villeneuve  and  Rupes- 
cissa  assert  that  one  part  of  the  grand  magistery 
will  convert  a  hundred  parts  of  a  base  metal  into 
gold;  Roger  Bacon,  a  hundred  thousand  parts; 
Isaac  of  Holland,  a  million.  Raymond  Lully 
states  that  philosopher's  stone  is  of  such  power 
that  even  the  gold  produced  by  means  of  it  will 
ennoble  an  infinitely  large  amount  of  a  base 
metal. 

It  is  hardly  necessary  to  state  that  a  prepara- 
tion of  such  potency  is  capable  of  effecting  any- 


The  Philosopher's  Stone  49 

thing  or  everything;  and  accordingly,  as  time 
went  on,  other  attributes  than  that  of  trans- 
mutation came  to  be  associated  with  it.  It  may 
be,  as  Boerhaave  surmises,  that  the  idea  of  a 
universal  medicine  had  its  origin  in  a  too  literal 
interpretation  of  Geber's  allegory  of  the  six 
lepers.  Be  this  as  it  may,  during  the  fourteenth 
and  fifteenth  centuries  the  philosopher's  stone 
was  gravely  prescribed  as  a  means  of  preserving 
health  and  prolonging  life.  In  case  of  illness 
one  grain  was  directed  to  be  dissolved  in  a  suffi- 
cient quantity  of  good  white  wine,  contained  in  a 
silver  vessel,  the  draught  to  be  taken  after  mid- 
night. Recovery  would  follow  after  an  interval 
depending  upon  the  severity  and  age  of  the 
complaint.  To  keep  in  good  health,  the  dose 
was  to  be  repeated  at  the  beginning  of  spring  and 
autumn.  "By  this  means,"  says  Daniel  Zacha- 
rias,  "one  may  enjoy  perfect  health  until  the 
end  of  the  days  assigned  to  one.  "  Isaac  of  Hol- 
land and  Basil  Valentine  are  equally  explicit,  but 
in  their  case  it  is  recommended  that  the  dose 
should  be  taken  once  a  month :  thus  life  would  be 
prolonged  "until  the  supreme  hour  fixed  by  the 
king  of  heaven."  Other  alchemists  were  not 
always  so  prudent  in  prophecy.  Artephius  gave 
the  limit  of  human  life  thus  prolonged  as  a  thou- 
sand years;  Gualdo,  a  Rosicrucian,  was  stated 
to  have  lived  four  hundred  years.  Raymond 
Lully  and  Salomon  Trismosin,  we  are  told,  re- 


50  History  of  Chemistry 

* 

newed  their  youth  by  means  of  it.  The  ad- 
vanced age  at  which  Noah  begat  children  could 
only  be  due,  says  Vincent  de  Beauvais,  to  his 
use  of  the  philosopher's  stone.  Dickinson  wrote 
a  learned  book  to  prove  that  the  great  age  of  the 
patriarchs  was  owing  to  the  same  secret. 

But  not  only  were  health  and  length  of  days 
the  fortunate  lot  of  him  who  possessed  the  philo- 
sopher's stone;  increase  of  wisdom  and  virtue 
equally  followed  from  its  use.  As  it  ennobled 
metals,  so  it  freed  the  heart  from  evil.  It  made 
men  as  wise  as  Aristotle  or  Avicenna,  sweetened 
adversity,  banished  vain-glory,  ambition,  and 
vicious  desires.  Adam  received  it  at  the  hands 
of  God,  and  it  was  given  also  to  Solomon,  al- 
though the  commentators  were  rather  exercised 
to  know  why,  as  he  possessed  the  philosopher's 
stone,  he  should  have  sent  to  Ophir  for  gold. 

It  would  serve  no  good  purpose  to  attempt  to 
describe  the  recipes  given  by  various  alchemists 
to  prepare  this  precious  substance.  With  an 
affectation  at  times  of  precision,  they  were 
purposely  obscure,  and  always  enigmatical.  As 
Boyle  said  of  them,  they  could  scarcely  keep 
themselves  from  being  confuted  except  by  keep- 
ing themselves  from  being  clearly  understood. 
One  example  of  their  recipes  must  suffice:  "To 
fix  quicksilver.  —  Of  several  things  take  2 ,  3  and 
3,  i;  i  to  3  is  4;  3,  2  and  i.  Between  4  and  3 
there  is  i;  3  from  4  is  i;  then  i  and  i,  3  and  4; 


The  Philosopher's  Stone  51 

i  from  3  is  2.  Between  2  and  3  there  is  i,  be- 
tween 3  and  2  there  is  i.  i,  i,  i,  and  i,  2,  2  and 
i,  i  and  i  to  2.  Then  i  is  i.  I  have  told  you 
all."  No  wonder,  after  an  equally  luminous 
explication,  a  pupil  of  Arnaud  de  Villeneuve 
should  have  exclaimed:  "But,  master,  I  do  not 
understand."  Upon  which  the  master  rejoined 
that  he  would  be  clearer  another  time. 

Nor  is  it  necessary  to  dilate  upon  the  other 
virtues  which  were  ascribed  at  various  times  to 
the  philosophical  powder,  as,  for  example,  its 
power  of  making  pearls  and  precious  stones,  or  of 
its  use  in  preparing  the  alkahest,  or  universal  sol- 
vent, invented  by  Paracelsus.  In  their  attempts 
to  fathom  the  depths  of  human  credulity  the 
alchemists  at  length  over-reached  themselves. 
The  idea  of  a  universal  solvent  carried  with  it,  as 
Kunkel  pointed  out,  its  own  refutation:  if  it  dis- 
solved everything,  no  vessel  could  contain  it. 
And  yet,  says  Boerhaave,  a  whole  library  could 
be  filled  with  writings  by  the  school  of  Paracel- 
sus on  the  alkahest.  From  the  latter  end  of  the 
sixteenth  century  repeated  attempts  were  made 
to  expose  the  pretensions  and  demonstrate  the 
absurdities  of  alchemy.  Among  its  adversaries 
may  be  cited  Thomas  Erastius,  Hermann 
Conringius,  and  the  Jesuit  Kircher.  Many  of 
their  dupes,  potentates  and  princes  who  were 
powerful  enough  to  exercise  it,  occasionally  vis- 
ited with  their  vengeance  those  who,  unmind- 


S2  History  of  Chemistry 

ful  of  the  injunctions  of  Albert  the  Great,  had 
traded  too  long  upon  their  credulity.  The 
Emperor  Rudolph  II.,  who  earned  the  title  of 
"The  Hermes  of  Germany, "  was  a  zealous  culti- 
vator of  alchemy,  and  had  a  well-equipped 
laboratory  in  his  palace  at  Prague,  to  which 
every  adept  was  welcome.  Ferdinand  III.  and 
Leopold  I.  were  also  patrons  of  the  hermetic  art, 
as  were  Frederick  I.  and  his  successor,  Frederick 
II.,  Kings  of  Prussia.  Indeed,  at  one  period 
nearly  every  Court  in  Europe  had  its  alchemist, 
with  the  privileges  of  the  Court  fool  or  the  poet 
laureate.  The  fraud  and  imposture  to  which 
the  practice  gave  rise  led  occasionally  to  the 
promulgation  of  stringent  laws  against  it,  and 
at  times  the  pursuit  of  operative  chemistry  be- 
came well-nigh  impossible  in  some  countries. 
In  the  fifth  year  of  the  reign  of  Henry  IV.  (1404) 
it  was  enacted  that  "  None  from  henceforth  shall 
use  to  multiply  gold  or  silver,  or  use  the  craft  of 
multiplication;  and  if  the  same  do  he  shall 
incur  the  pain  of  felony. ' '  According  to  Watson, 
the  true  reason  for  passing  this  Act  was  not  an 
apprehension  that  men  should  ruin  their  for- 
tunes by  endeavouring  to  make  gold,  but  a 
jealousy  lest  Government  should  be  above  asking 
aid  of  the  subject.  At  the  same  time,  letters 
patent  were  granted  to  several  persons,  per- 
mitting them  to  investigate  the  universal  medi- 
cine and  perform  the  transmutation  of  metals. 


The  Philosopher's  Stone  53 

Alphonse  X.,  of  Castille,  the  author  of  the 
Key  of  Wisdom,  practised  alchemy.  Henry  VI., 
of  England,  and  Edward  IV.  had  dealings  with 
adepts.  Even  Elizabeth  Tudor,  who  was  a 
shrewd  enough  sovereign,  had  the  notorious  Dr. 
Dee  in  her  pay.  Charles  VII.  and  Charles  IX.,  of 
France,  Christian  IV.,  of  Denmark,  and  Charles 
XII.,  of  Sweden,  sought  to  replenish  their  ex- 
hausted treasuries  by  the  aid  of  the  philoso- 
pher's stone.  If  princes  eventually  learned 
not  to  put  their  trust  in  alchemists,  alchemists 
learned  equally  to  their  cost  not  to  put  their 
trust  in  princes.  Duke  Julius,  of  Brunswick,  in 
1575,  burnt  a  female  alchemist,  Marie  Ziglerin, 
who  had  failed  in  her  promise  to  furnish  him  with 
a  prescription  for  the  making  of  gold.  David 
Benther  killed  himself  to  escape  the  fury  of  the 
Elector  Augustus,  of  Saxony.  Bragadino  was 
hanged  at  Munich  in  1590  by  the  Elector  of 
Bavaria.  Leonard  Thurneysser,  who  gained  an 
evil  notoriety  in  his  day  as  one  of  the  most 
unscrupulous  of  the  followers  of  Paracelsus,  and 
who  amassed  considerable  wealth  by  the  sale  of 
cosmetics  and  nostrums,  was  deprived  of  his  ill- 
gotten  gains  in  1584  by  the  Elector  of  Branden- 
burg, and  died  in  misery  in  the  convent.  Borri, 
a  Milanese  adventurer,  who  had  deceived 
Frederick  III.,  of  Denmark,  was  imprisoned  for 
years  by  that  monarch,  and  died  in  captivity  in 
1695.  William  de  Krohnemann  was  hanged  by 


54  History  of  Chemistry 

the  Margrave  of  Byreuth,  who,  with  grim  irony, 
caused  the  inscription  to  be  fixed  to  his  gib- 
bet: "I  once  knew  how  to  fix  mercury,  and  now 
I  am  myself  fixed.  "  Hector  de  Klettenberg  was 
beheaded  in  1720  by  Augustus  II.,  King  of 
Poland. 

All  the  followers  of  Hermes  were  not  so  wary 
or  so  candid  as  the  artist  who  declined  an  invita- 
tion to  visit  the  Court  of  Rudolph  II.,  saying: 
"  If  I  am  an  adept,  I  have  no  need  of  the 
Emperor;  if  I  am  not,  the  Emperor  has  no  need 
of  me."  Well  might  John  Clytemius,  Abbot  of 
Wiezenberg,  write :  "  Vanitas,fraus,  dolus,  sophis- 
ticatio,  cupiditas,  falsitas,  mendacium,  stultitia, 
paupertas,  desesperatio,  fuga,  proscriptio  et  men- 
dicitas,  perdis&que  sunt  chemice." 

Despite  the  attacks  of  Kunkel,  Boerhaave, 
the  elder  Geoffroy,  Klaproth,  and  other  chemists 
of  influence  and  repute,  alchemy  died  hard.  It 
found  believers  in  England  until  near  the  close 
of  the  eighteenth  century,  and  was  professed 
even  by  a  Fellow  of  the  Royal  Society  —  Dr. 
James  Price,  of  Guildford,  who,  in  chagrin  at  the 
exposure  of  his  pretensions,  put  an  end  to  his 
existence  in  1783.  Hermetic  societies  existed  in 
Westphalia,  at  Konigsberg,  and  at  Carlsruhe 
down  to  the  first  decade  of  the  nineteenth  cen- 
tury. M.  Chevreul,  who  lived  well  into  that 
century,  relates  that  he  knew  of  several  persons 
who  were  convinced  of  the  truth  of  alchemy, 


The  Philosopher's  Stone  55 

among  them  "  generals,  doctors,  magistrates, 
and  ecclesiastics."  The  strange  medley  of  al- 
chemy, theosophy,  thaumaturgy,  and  cabalisti- 
cism  professed  by  Christian  Rosenkreuz  is  not 
without  its  adherents,  even  in  this  twentieth 
century. 

If  the  baser  metals  have  not  been  made  to 
furnish  gold,  truth  at  least  has  followed  from 
the  practice  of  error.  This  is  the  only  trans- 
mutation which  the  art  of  Hermes  has  succeeded 
in  effecting.  To  err  is  human.  Although  al- 
chemy is  not  without  its  special  interest  as  one  of 
the  most  remarkable  aberrations  in.  the  history 
of  science,  some  of  its  practitioners,  it  must  be 
admitted,  deceived  only  themselves:  if  mis- 
guided, they  were  at  least  honest,  and  pursued 
their  calling  in  a  settled  conviction  of  the  sound- 
ness of  their  faith.  Although  they  never  reached 
their  goal  —  the  discovery  of  the  Philosopher's 
Stone  and  the  Elixir  of  Life  —  their  labours  were 
not  wholly  vain,  for  many  new  and  unexpected 
facts  came  to  light  as  the  result  of  their  assiduity. 

"Credulity  in  arts  and  opinions,"  wrote  Lord 
Bacon  in  De  Augmentis  Scientiarum, 

is  likewise  of  two  kinds  —  viz.,  when  men  give 
too  much  belief  to  arts  themselves,  or  to  certain 
authors  in  any  art.  The  sciences  that  sway  the 
imagination  more  than  the  reason  are  princi- 
pally three  —  viz.,  astrology,  natural  magic, 
and  alchemy.  .  .  .  Alchemy  may  be  compared 
to  the  man  who  told  his  sons  that  he  had  left 


56  History  of  Chemistry 

them  gold,  buried  somewhere  in  his  vineyard; 
while  they  by  digging  found  no  gold,  but  by 
turning  up  the  mould  about  the  roots  of  the 
vines  procured  a  plentiful  vintage.  So  the 
search  and  endeavours  to  make  gold  have 
brought  manv  useful  inventions  of  light. 


CHAPTER  V 
IATRO-CHEMISTRY 

'"THE  term  "  iatro-chemistry "  denotes  a  parti- 
*  cular  phase  in  the  history  of  medicine  and 
of  chemistry.  The  iatro-chemists  were  a  school 
of  physicians  who  sought  to  apply  chemical 
principles  to  the  elucidation  of  vital  phenomena. 
According  to  them,  human  illnesses  result  from 
abnormal  chemical  processes  within  the  body, 
and  these  could  only  be  counteracted  by  appro- 
priate chemical  remedies.  Although  this  idea 
did  not  originate  with  him,  the  chief  exponent 
of  this  school  is  commonly  said  to  be  Paracelsus. 
A  man  of  violent  passions,  coarse,  drunken, 
arrogant,  and  unscrupulous,  Philippus  Aureolus 
Theophrastus  Paracelsus  Bombastus  von  Hohen- 
heim  —  to  give  him  his  full  name  —  would  seem 
to  have  possessed  none  of  the  attributes  needed 
by  the  successful  leader  of  an  intellectual 
revolution. 

Born  at  Etzel  in  Switzerland  in  1493,  the  son 
of  a  physician,  William  Bombast  von  Hohen- 
heim,  who  combined  the  practice  of  astrology 
with  that  of  alchemy,  Paracelsus,  even  as  a 
youth,  became  a  wanderer,  passing  from  pro- 
vince to  province  and  cloister  to  cloister,  living 

57 


58  History  of  Chemistry 

by  telling  fortunes  and  practising  sometimes  as  a 
quack  and  at  other  times  as  an  army  surgeon, 
and  gaining,  as  he  tells  us,  much  curious  infor- 
mation from  old  women,  gipsies,  conjurers,  and 
chemists.  If  we  may  trust  his  own  account  of 
himself,  he  had,  before  he  was  thirty-three,  wan- 
dered over  the  whole  of  Europe,  and  even  into 
Africa  and  Asia,  everywhere  performing  miracu- 
lous cures  and  constantly  getting  into  trouble. 
In  1526  he  secured  the  appointment  of  Professor 
of  Physic  in  the  University  of  Basle,  and  signal- 
ised his  occupancy  of  the  chair  by  a  course  of 
lectures  —  a  farrago  of  confused  German  and 
barbarous  Latin  —  in  w^hich  he  assailed  with 
extraordinary  vigour  and  unexampled  coarse- 
ness the  medical  system  of  the  school  of  Galen. 
Scandalised  as  his  professional  brethren  might 
be,  Paracelsus  expressed,  intentionally  or  unin- 
tentionally, the  feeling  of  impatience  with  which 
the  laity  viewed  a  system  of  therapeutics  based 
only  on  tradition.  In  this  revolt  against  author- 
ity he  initiated  a  movement  which,  whatever 
might  have  been  its  influence  on  medicine,  served 
eventually,  under  the  guidance  of  worthier  men, 
to  emancipate  chemistry  from  the  thraldom  of 
alchemy. 

Paracelsus  did  little  more  than  initiate.  Al- 
though his  many  tracts  show  that  he  was  fami- 
liar with  nearly  every  chemical  preparation  of 
his  time,  many  of  which  he  used  in  his  practice, 


latro-Chemistry  59 

he  added  no  new  substance  to  science.  A  man 
of  great  ability  and  extraordinary  talent,  he 
squandered  his  powers  in  dissipation.  His  in- 
temperate conduct  soon  lost  him  his  chair  at 
Basle;  and,  after  an  ignoble  quarrel  with  the 
magistracy,  he  fled  the  town,  and,  resuming  his 
wandering  life,  died,  under  wretched  circum- 
stances, at  Salzburg,  in  his  forty-eighth  year. 

Space  will  not  permit  of  any  account  of  the 
philosophical  opinions  of  Paracelsus  —  of  his 
mysticism,  his  theosophy,  -  his  pantheism,  his 
extraordinary  doctrine  of  the  Archaeus  and 
Tartarus,  his  association  of  astrology  with  med- 
icine. His  chief  merit  lies  in  his  insistence  that 
the  true  function  of  chemistry  was  not  to  make 
gold  artificially,  but  to  prepare  medicines  and 
substances  useful  to  the  arts.  He  thereby  made 
chemistry  indispensable  to  medicine,  and  thence- 
forward chemistry  began  to  be  taught  in  the 
universities  and  in  the  schools  as  an  essential 
part  of  a  medical  education. 

Paracelsus  is  usually  regarded  as  a  typical 
alchemist  —  the  kind  of  man  made  familiar  to 
us  by  the  paintings  of  Teniers,  Van  Ostade,  and 
Stein  —  a  boorish,  maudlin  knave,  who  divided 
his  time  between  the  pothouse  and  the  kitchen 
in  which  he  prepared  his  extracts,  simples,  tinc- 
tures, and  the  other  nostrums  which  he  palmed 
off  upon  a  credulous  world,  as  ignorant  and 
superstitious  as  himself.  There  is  much  in  the 


60  History  of  Chemistry 

personal  history  of  Paracelsus  that  serves  to 
justify  such  a  view  of  him.  That  he  was  in  the 
main  an  impudent  charlatan,  ignorant,  vain,  and 
pretentious,  there  can  be  little  doubt.  He  had 
an  astonishing  audacity  and  a  boundless  effron- 
tery; and  it  was  largely  by  the  exercise  of  these 
qualities  that  he  secured  such  professional  suc- 
cess as  he  enjoyed. 

To  judge  from  the  number  of  the  published 
works  associated  with  his  name,  he  was  an  ac- 
tive and  industrious  writer.  Considering  that 
during  the  greater  part  of  his  waking  time  he 
was  more  or  less  intoxicated,  it  is  difficult  to 
conceive  what  opportunity  he  had  for  composing 
them.  Only  one  or  two  are  known  to  be  genuine. 
These,  according  to  Operinus,  his  publisher,  he 
dictated;  and  from  their  incoherence  and  ob- 
scurity, their  mystical  jargon,  and  misuse  of 
terms,  they  read  like  the  ravings  of  one  whom 
drunkenness  had  deprived  of  reason.  Many  of 
the  tracts  and  larger  works  appeared  after  his 
death  —  some  of  them  years'  after;  and  there  is 
no  certain  proof  that  he  was  the  actual  author. 
Even  if  we  regard  them  as  supposititious,  tlte 
fact  that  they  should  be  published  under  his 
name  is  significant  of  the  influence  and  notori- 
ety which  this  extraordinary  man  succeeded  in 
achieving  during  his  short  and  chequered  career. 

The    immediate    followers    of    Paracelsus  - 
among  whom  may  be  named  Thurneysser,  Dorn, 


latro-Chemistry  61 

Severinus,  Duchesne  —  distinguished  them- 
selves only  by  the  boldness  with  which  they 
promulgated  his  doctrines,  and  the  unscrupulous 
use  which  they  made  of  his  methods.  They  were 
all  zealous  anti-Galenists,  who  professed  to  be- 
lieve that  the  sum  and  perfection  of  human  know- 
ledge was  to  be  found  in  the  Cabala,  and  that 
-the  secrets  of  magical  medicine  were  contained 
in  the  Apocalypse.  They  adopted  pantheism 
in  all  its  grossness:  everything  that  exists  eats, 
drinks,  and  voids  excrement;  even  minerals  and 
liquids  assimilate  food,  and  eliminate  what  they 
do  not  incorporate.  Sylphs  inhabit  the  air, 
nymphs  the  water,  pigmies  the  earth,  and  sala- 
manders the  fire.  Thus  even  the  Aristotelian 
elements  were  animated.  Mercury,  sulphur, 
and  salt  were,  according  to  Paracelsus,  the  pri- 
mal principles  which  entered  into  the  composi- 
tion of  all  things,  material  and  immaterial,  visible 
and  invisible.  The  following  so-called  "har- 
monies" were  essential  articles  of  faith  with  a 
Paracelsian  :— 

Soul  Spirit  Body 

Mercury  Sulphur  Salt 

Water  Air  Earth 

The  laws  of  the  Cabala  were  held  to  explain  the 
functions  of  the  body.  The  sun  rules  the  heart, 
the  moon  the  brain,  Jupiter  the  liver,  Saturn  the 
spleen,  Mercury  the  lungs,  Mars  the  bile,  Venus 


62  History  of  Chemistry 

the  kidneys.  Gold  was  a  specific  against  dis- 
eases of  the  heart;  the  liquor  of  Luna  (solution 
of  silver)  cures  diseases  of  the  brain.  "The 
remedies,"  said  Paracelsus,  "are  subjected  to 
the  will  of  the  stars,  and  directed  by  them. 
You  ought,  therefore,  to  wait  until  heaven  is 
favourable  before  ordering  a  medicine." 

The  Paracelsian  physicians,  for  the  most  part/ 
were  a  set  of  dangerous  fanatics,  who,  in  their  con- 
tempt for  the  principles  of  Hippocrates,  Galen, 
and  Avicenna,  and  in  their  reckless  use  of 
powerful  remedies,  many  of  them  metallic  poi- 
sons, wrought  untold  misery  and  mischief.  The 
inevitable  reaction  set  in,  and  certain  of  the 
faculties,  particularly  that  of  Paris,  prohibited 
their  licentiates,  under  severe  penalties,  from 
using  chemical  remedies.  It  is  not  to  be  sup- 
posed, however,  that  all  iatro-chemists  were 
unscrupulous  charlatans.  Some  of  them  clearly 
perceived  the  significance  and  true  value  of  the 
movement  which  Paracelsus  may  be  credited 
with  having  originated. 

Andreas  Libavius,  or  Libau,  originally  a  phy- 
sician, born  in  Halle,  is  best  known  by  his 
Alchymia,  published  in  1595,  which  contains  an 
account  of  the  main  chemical  facts  known  in  his 
time,  and  is  written  in  clear  and  intelligible  lan- 
guage, in  strong  contrast  to  the  mystery  and 
obscurity  of  his  predecessors.  He  was  the 
discoverer  of  stannic  chloride,  still  know  as  the 


latro-Chemistry  63 

fuming  liquor  of  Libavius,  and  described  a 
method  of  preparing  oil  of  vitriol  in  principle 
identical  with  that  now  made  use  of  on  a  manu- 
facturing scale.  He  died  in  1616. 

John  Baptist  van  Helmont,  a  scion  of  a  noble~\ 
Brabant  family,  was  born  in  Brussels  in  1577. 
After  studying  philosophy  and  theology  at  the 
University  of  Louvain,  he  directed  his  attention 
to  medicine,  and  made  himself  familiar,  in  turn, 
with  every  system  from  Hippocrates  to  Para- 
celsus. Having  spent  some  time  in  travel,  he 
settled  on  his  estate  at  Vilvorde,  and  occupied 
himself  with  laboratory  pursuits  until  his  death 
in  1644. 

Van  Helmont  was  a  scholarly,  studious  man, 
and  a  philosopher.  A  theosophist  and  prone  to 
mysticism,  he  had  many  of  the  mental  character- 
istics of  Paracelsus,  without  his  fanaticism  and-. 
overweening  egotism.  He  narrowed  the  num- 
ber of  Aristotle's  elements  down  to  one,  and,  like 
Thales,  considered  water  to  be  the  true  principle 
of  all  things,  supporting  his  theory  by  ingenious 
observations  on  the  growth  of  plants  (see  p.  20). 
He  first  employed  the  term  gas,  and  was  aware 
of  the  existence  of  various  aeriform  substances, 
anticipating  Hales,  who  has  been  styled  the 
father  of  pneumatic  chemistry,  in  the  discovery 
of  many  gaseous  phenomena.  He  gave  an  ac- 
curate description  of  carbonic  acid  gas,  which  he 
termed  gas  sylvestre,  and  showed  that  it  is  pro- 


64  History  of  Chemistry 

duced  from  limestone  and  potashes  in  the  fermen- 
tation of  wine  and  beer,  and  that  it  is  formed 
in  the  body  and  in  the  earth.  The  doctrines 
of  the  iatro-chemists  were  further  spread  by 
Sylvius  in  Holland,  and  by  Willis  in  England. 

Francis  de  le  Boe  Sylvius,  born  at  Hanau 
in  1614,  became  Professor  of  Medicine  in  the 
University  of  Leyden,  where  he  exercised  great 
influence  as  a  teacher  until  his  death  in  1672. 
Medicine  he  treated  simply  as  a  branch  of  ap- 
plied chemistry,  and  the  vital  processes  of  the 
animal  body  as  purely  chemical.  He  freed  the 
theory  of  physic  from  much  of  the  mystical 
absurdity  introduced  into  it  by  Paracelsus  and 
van  Helmont,  and  by  his  practice  brought  chem- 
ical remedies  once  more  into  vogue.  He  was 
aware  of  the  distinction  between  venous  and 
arterial  blood,  and  that  the  red  colour  of  the 
latter  was  due  to  the  influence  of  air.  Com- 
bustion and  respiration  he  regarded  as  analogous 
phenomena. 

Thomas  Willis  was  born  in  Wiltshire  in  1621, 
and  while  a  student  at  Christchurch  bore  arms  in 
the  Royalist  army  when  Oxford  was  garrisoned 
for  Charles  I.  In  1660  he  became  Sedleian 
Professor  of  Natural  Philosophy,  and  ultimately 
settled  in  London  as  a  physician.  He  died  in 
1675,  and  was  buried  in  Westminster  Abbey. 

Willis  imagined  that  all  vital  actions  were 
due  to  different  kinds  of  fermentation,  and  that 


latro-Chemistry  65 

diseases  were  caused  by  abnormalities  in  the 
fermentative  process.  Although  a  Paracelsian 
as  regards  his  theory  of  the  constitution  of  mat- 
ter, he  followed  Sylvius  and  his  pupil  Tachenius 
in  banishing  mysticism  from  medicine.  He 
was  a  skilful  anatomist,  and  gave  the  first  ac- 
curate description  of  the  brain  and  nerves. 

Other  notable  iatro-chemists  were  Angelus 
Sala,  Daniel  Sennert,  Turquet  de  Mayerne  (who 
became  body  physician  to  James  I.),  Oswald 
Croll,  Adrian  van  Mynsicht,  and  Thomas  Lieber. 
Croll  introduced  the  use  of  potassium  sulphate 
and  succinic  acid  into  medicine,  and  Van  Myn- 
sicht that  of  tartar  emetic.  Various  antimonial 
preparations  had  previously  been  employed  by 
chemical  physicians  since  the  time  of  Basil  Val- 
entine, despite  the  ban  of  the  Parliament  of 
Paris  on  their  use. 

The  chief  service  of  iatro-chemistry  to  science 
consisted  in  its  influence  in  bringing  chemistry 
within  the  range  of  professional  study,  whereby 
a  great  extension  in  its  pursuit  was  effected, 
with  the  result  that  a  largely  increased  number 
of  substances  was  discovered.  Moreover,  this 
wider  experience  of  chemical  processes  famil- 
iarised workers  with  chemical  phenomena  in 
general,  and  thereby  contributed  to  lay  the  foun- 
dations of  a  general  theory  of  chemical  action, 
which  a  succeeding  age  strove  to  complete. 

During  the  period  of  iatro-chemistry,  which 


66  History  of  Chemistry 

may  be  said  to  have  extended  from  the  first  quar- 
ter of  the  sixteenth  century  to  the  latter  half 
of  the  seventeenth,  chemistry  was  advanced 
along  practical  lines  by  the  labours  of  many 
men,  chief  of  whom  were  Agricola  the  metallur- 
gist, Pali ssy  the  potter,  and  Glauber  the  technol- 
ogist. These  men  were  primarily  experimental 
chemists,  who  took  little  or  no  part  in  the  fruit- 
less polemics  of  the  period,  but  followed  their 
avocation  in  the  true  spirit  of  investigators,  and 
thereby  enriched  science  with  many  new  and 
well-ascertained  facts. 

George  Agricola,  born  at  Glauchau  in  Saxony 
in  1494,  was  a  contemporary  of  Paracelsus. 
After  studying  medicine  at  Leipzig,  he  devoted 
himself  to  metallurgy  and  mineralogy,  first  at 
Joachimsthal,  and  published  a  number  of  works 
which  were  long  deservedly  regarded  as  the 
leading  treatises  on*  these  subjects. 

In  his  Libri  XII.  de  re  Metallica  he  gives  an 
account  of  what  was  known  in  his  time  respect- 
ing the  extraction,  preparation,  and  testing  of 
ores.  He  describes  the  smelting  of  copper  and 
the  recovery  of  the  silver  which  might  be  as- 
sociated with  it.  He  also  describes  methods 
of  obtaining  quicksilver,  and  of  purifying  it  by 
treatment  with  salt  and  vinegar.  He  gives  a 
full  description  of  the  method  of  obtaining  gold 
by  amalgamation,  and  of  recovering  the  mer- 
cury by  distillation.  He  gives  accounts  of  the 


latro-Chemistry  67 

smelting  of  lead,  tin,  iron,  bismuth,  and  anti- 
mony, and  describes  the  manufacture  of  salt, 
nitre,  alum,  and  green  vitriol. 

The  whole  work,  which  is  of  folio  size,  is 
illustrated  by  wood-cuts,  which  give  a  faithful 
idea  of  the  nature  of  the  several  operations,  and 
of  the  character  of  furnaces,  trompes,  bellows, 
and  tools  employed  in  them.  It  is  by  far  the 
most  important  technical  work  of  the  sixteenth 
century,  and  it  exercised  great  influence  on  the 
art  of  metallurgy.  The  descriptions  —  at  least 
as  regards  European  processes  —  are  evidently 
the  result  of  personal  observation.  Agricola 
visited  the  mines,  and  faithfully  noted  the  differ- 
ent methods  of  sorting  and  washing  the  ores, 
the  characters  of  which  he  accurately  describes. 
His  accounts  of  the  various  smelting  operations 
are  so  detailed  that  it  is  obvious  they  must  have 
been  put  together  after  personal  inquiry.  The 
study  of  metallurgy,  indeed,  was  the  main  object 
of  his  life;  and  he  devoted  to  its  pursuit  even  the 
pension  which  had  been  settled  on  him  by 
Maurice,  Elector  of  Saxony.  He  became  Mayor 
of  Chemnitz,  died  there  in  1555,  and  was  buried 
at  Zeitz. 

Bernard  Palissy  lived  throughout  the  greater 
portion  of  the  sixteenth  century.  Although 
not  a  professed  chemist,  nor  a  follower  of  any 
particular  school,  he  was  an  ardent  self-taught 
experimentalist  and  a  keen  and  accurate  ob- 


68  History  of  Chemistry 

server,  who  greatly  enriched  ceramic  art  by  his 
discoveries. 

Johann  Rudolf  Glauber  was  born  at  Karlstadt, 
in  Bavaria,  in  1604,  and  after  a  restless  life  died 
in  Amsterdam  in  his  sixty-fourth  year.  He 
published  an  encyclopaedia  of  chemical  processes, 
in  which  he  describes  the  preparation  of  a  great 
variety  of  substances  of  technical  importance. 
The  greater  number  of  the  pharmacopoeias  of 
the  seventeenth  century  are  indebted  to  him  for 
their  descriptions  of  the  mode  of  manufacture 
of  their  official  preparations.  He  discovered 
sodium  sulphate  —  his  sal  mirabile,  still  fre- 
quently named  after  him  —  and  introduced  it 
into  medicine. 

During  this  period  the  common  mineral  acids 
—  sulphuric,  hydrochloric,  and  nitric  —  became 
ordinary  articles  of  commerce,  and  were  used 
in  the  manufacture  of  a  number  of  useful  prod- 
ucts, chiefly  inorganic  salts.  A  considerable 
number  of  metallic  oxides  were  also  in  common 
use,  and  were  applied  to  a  variety  of  purposes  in 
the  arts.  The  knowledge  of  definite  organic 
substances  was  much  more  limited.  Acetic  acid 
had  long  been  known,  but  was  first  obtained  in  a 
concentrated  form  during  this  period  by  the  dis- 
tillation of  verdigris.  A  number  of  other  acetates 
were  also  known,  as  well  as  certain  tartrates  — 
as,  for  example,  salt  of  sorrel,  Rochelle  or  seig- 
nette  salt,  and  tartar  emetic.  Succinic  and 


latro  Chemistry  69 

benzole  acid  were  introduced  into  medicine,  and 
Tachenius  discovered  one  of  the  characteristic 
acids  of  fat  and  oil  (stearic  acid).  Spirit  of 
wine  was,  of  course,  largely  made  and  used 
in  the  preparation  of  tinctures  and  essences. 
Ether,  originally  known  as  oleum  vitrioli  dulce 
verum,  was  first  discovered  by  Valerius  Cordus ; 
and  a  mixture  of  it  with  alcohol,  long  known  as 
Hoffmann's  drops,  appears  to  have  been  em- 
ployed as  a  medicine  by  Paracelsus. 


CHAPTER   VI. 

11  THE  SCEPTICAL  CHEMIST":  THE  DAWN   OF 
SCIENTIFIC  CHEMISTRY. 

PHE  latter  half  of  the  seventeenth  century 
*  was  a  remarkable  period  in  the  history  of 
the  intellectual  development  of  Europe.  At  that 
time  nearly  every  department  of  human  know- 
ledge seemed  to  have  become  permeated  by  an 
eager  spirit  of  scepticism,  inquiry,  and  reform. 
The  foundation  of  the  Royal  Society  of  London 
for  Improving  Natural  Knowledge,  the  Acca- 
demia  del  Cimento  of  Florence,  the  Academic 
Royale  at  Paris,  the  Berlin  Academy,  all  within 
a  few  years  of  each  other,  was  significant  of  the 
times.  Chemistry  was  no  longer  to  be  a  sacred 
mystery,  to  be  known  only  to  priests,  and  its 
secrets  jealously  guarded  by  them.  Science  had 
chafed  under  the  domination  of  the  schoolmen; 
it  was  now  contemptuous  of  the  dialectics  of 
the  Spagyrists.  Experimentarian  philosophy 
became  even  fashionable ;  and  the  purely  deduc- 
tive methods  of  the  Peripatetics  gradually  gave 
place  to  the  only  sound  method  of  advancing 
natural  knowledge.  The  supremacy  of  the  old 
philosophy  may  be  said  to  have  been  first 
distinctly  challenged  by  Robert  Boyle.  The 
70 


"  The  Sceptical  Chemist  "         71 

appearance  in  1661  of  his  book,  The  Sceptical 
Chemist,  marks  a  turning-point  in  the  history 
of  chemistry.  The  "  Chemico-physical  Doubts 
and  Paradoxes"  raised  by  Boyle  "touching  the 
experiments  whereby  vulgar  Spagyrists  are 
wont  to  endeavour  to  evince  their  Salt,  Sulphur, 
and  Mercury  to  be  the  true  Principles  of  Things, " 
eventually  sealed  the  fate  of  the  doctrine  of  the 
tria  prima,  and  of  the  tenets  of  the  school  of 
Paracelsus. 

In  this  treatise  Boyle  sets  out  to  prove  that 
the  number  of  the  peripatetic  elements  or 
principles  hitherto  assumed  by  chemists  is,  to 
say  the  least,  doubtful.  The  words  "element" 
and  "principle"  are  used  by  him  as  equivalent 
terms,  and  signify  those  primitive  and  simple 
bodies  of  which  compounds  may  be  said  to  be 
composed,  and  into  which  these  compounds  are 
ultimately  resolvable.  He  considered  that  the 
matter  of  all  bodies  was  originally  divided  into 
small  particles  of  different  shapes  and  sizes,  and 
that  these  particles  might  unite  into  small 
"parcels,"  not  easily  separable  again;  that  a 
great  variety  of  compounds  may  arise  from  a  few 
ingredients;  that  various  substances  are  obtain- 
able from  bodies  by  fire;  that  fire  is  not  the 
true  and  genuine  analyser  of  bodies,  since  it  does 
not  separate  the  principles  of  a  body,  but 
variously  alters  its  nature ;  and  that  some  things 
obtained  from  a  body  by  fire  were  not  its  proper 


72  History  of  Chemistry 

or  essential  ingredients.  Three  is  not  precisely 
and  universally  the  number  of  the  distinct  sub- 
stances or  elements  into  which  all  compound 
bodies  are  resolvable  by  fire,  inasmuch  as  some 
bodies  afford  more  than  three  principles.  Earth 
and  water  are  as  much  chemical  principles  as 
salt,  sulphur,  and  mercury.  Even  the  limitation 
to  five  chemical  principles  is  too  narrow.  Such 
is  proved  to  be  the  case  by  the  mode  in  which 
bodies,  animals  and  vegetable,  grow,  and  by  the 
analysis  of  minerals  and  metals.  The  chemical 
theory  of  "  qualities"  of  the  Spagyrists  is  narrow, 
defective,  and  uncertain;  supposes  things  not 
proved;  is  often  superfluous,  and  frequently 
contradicts  the  phenomena  of  nature.  The 
" principles"  found  in  bodies  cannot  be  the 
cause  of  their  qualities,  since  contrary  qualities 
are  ascribed  to  the  same  body.  He  concludes, 
therefore,  that  the  Paracelsian  elements  - 
their  "salt,"  " sulphur, ".  and  "mercury" 
are  not  the  first  and  most  simple  principles 
of  bodies;  but  that  these  consist,  at  most, 
of  concretions  of  corpuscles  or  particles  more 
simple  than  they,  and  possessing  the  radical 
and  universal  properties  of  volume,  shape,  and 
motion. 

Robert  Boyle,  fourteenth  child  and  the 
seventh  and  youngest  son  of  Richard  the 
" Great"  Earl  of  Cork,  and  Lord  High  Chancellor 
of  Ireland,  was  born  at  Lismore  in  1626.  He 


ROBERT  BOYLE. 
From  a  painting  by  F.  Kerseboom  in  the  possesion  of  the  Royal  Society. 


73 


74  History  of  Chemistry 

was  educated  at  Eton  under  Sir  Henry  Wotton, 
and,  after  spending  some  years  on  the  Continent, 
settled  at  Stalbridge  in  Dorset,  where  he  owned 
a  manor.  He  became  a  member  of  what  was 
known  as  the  Invisible  College,  a  small  associa- 
tion of  men  interested  in  the  new  philosophy, 
who  met  at  each  other's  houses  in  London,  and 
occasionally  at  Gresham  College,  "to  discourse 
and  consider  of  philosophical  inquiries  and  such 
as  related  thereunto."  The  meetings  were 
subsequently  held  in  Oxford,  and  Boyle  took  up 
his  residence  there  in  1654.  Here  —  in  associa- 
tion with  Wilkins;  John  Wallis  and  Seth  Ward, 
the  two  Savilian  Professors  of  Geometry  and 
Astronomy;  Thomas  Willis,  the  physician,  then 
student  of  Christ  Church;  Christopher  Wren, 
then  Fellow  of  All  Souls'  College;  Goddard, 
Warden  of  Merton;  and  Ralph  Bathurst,  Fellow 
of  Trinity,  and  afterwards  its  President  —  they 
sought  to  cultivate  the  new  philosophy,  "being 
satisfied  that  there  was  no  certain  way  of 
arriving  at  any  competent  knowledge  unless 
they  made  a  variety  of  experiments  upon  natural 
bodies.  In  order  to  discover  what  phenomena 
they  would  produce,  they  pursued  that  method 
by  themselves  with  great  industry,  and  then 
communicated  their  discoveries  to  each  other/' 
The  Invisible  College  eventually  grew  into  the 
Royal  Society,  which  received  its  charter  in  1663. 
Boyle  removed  to  London  in  1668,  and  died 


"  The  Sceptical  Chemist "          75 

there  on  December  3ist,  1691,  in  the  sixty-fifth 
year  of  his  age. 

A  man  of  integrity,  modest,  simple,  and  un- 
assuming, Boyle  was  an  assiduous  and  true  stu- 
dent of  science,  and  practically  the  whole  of  his 
life  was  given  to  its  pursuit.  His  social  position, 
his  example,  the  purity  of  his  private  life,  and 
the  fame  of  his  discoveries  made  his  personal 
influence  very  considerable,  to  the  great  ad- 
vantage of  science  in  this  country.  His  ex- 
perimental work  was  of  a  high  order.  He 
introduced  the  air-pump  into  England,  and  his 
"pneumatical  engine"  enabled  him  to  discover 
many  of  the  fundamental  properties  of  a  gas, 
notably  the  relation  of  its  volume  to  pressure. 
He  also  discovered  the  dependence  of  the  boiling 
point  of  a  liquid  upon  atmospheric  pressure, 
explained  the  action  of  the  syphon,  the  effect  of 
the  air  on  the  vibration  of  a  pendulum  and  on 
the  propagation  of  sound,  and  made  experiments 
on  the  nature  of  flame,  and  on  the  relation  of 
air  to  combustion  and  respiration:  In  his  His- 
tory of  Fluidity  he  seeks  to  show  that  a  body 
seems  to  be  fluid  by  consisting  of  corpuscles 
touching  one  another  only  in  some  parts  of  their 
surfaces;  whence,  by  reason  of  the  numerous 
spaces  between  them,  they  easily  glide  along 
each  other  till  they  meet  with  some  resisting 
body  to  whose  internal  surface  they  exquisitely  ac- 
commodate themselves.  He  considers  the  requi- 


76  History  of  Chemistry 

sites  of  fluidity  to  be  chiefly  these :  The  small- 
ness  of  the  component  particles,  their  determinate 
figure,  the  vacant  spaces  between  them,  and 
the  fact  of  their  being  agitated  variously  and 
apart  by  their  own  innate  motion  or  by  some 
thinner  substance  which  tosses  them  about  in 
its  passage  through  them.  His  published  works 
contain  many  well-authenticated  chemical  facts, 
which  are  commonly  held  to  be  the  discovery  of 
a  later  time.  He  prepared  acetone  by  the  dis- 
tillation of  the  acetates  of  lead  and  lime ;  and  he 
isolated  methyl  alcohol' from  the  products  of  the 
destructive  distillation  of  wood.  He  was  one  of 
the  earliest  to  insist  on  the  necessity  of  studying 
the  forms  of  crystals.  He  saw  in  their  formation 
proof  that  the  internal  motions,  configuration, 
and  position  of  the  integral  parts  are  all  that  is 
necessary  to  account  for  alterations  and  diver- 
sities in  outward  character.  Some  of  the  stock 
illustrations  of  our  lecture-rooms  were  of  his 
contrivance.  Thus  he  illustrated  the  expansive 
power  of  freezing  water  by  bursting  a  plugged 
gun-barrel  filled  with  water  by  solidifying  the 
water  by  means  of  a  mixture  of  snow  and  salt  — 
a  freezing  mixture  which  he  first  introduced. 

Boyle  was  the  first  to  formulate  our  present 
conception  of  an  element  in  contradistinction 
to  that  of  the  Greeks  and  the  schoolmen  who 
influenced  the  theories  of  the  iatro-chemists. 
In  the  sense  understood  by  him,  the  Aristotelian 


"  The  Sceptical  Chemist  "         77 

I 

elements  were  not  true  elements,  nor  were  the 
salt,  sulphur,  and  mercury  of  the  school  of 
Paracelsus.  He  was  also  the  first  to  define  the 
relation  of  an  element  to  a  compound,  and  to 
draw  the  distinction  we  still  make  between  com- 
pounds and  mixtures.  He  revived  the  atomic 
hypothesis,  and  explained  chemical  combination 
on  the  basis  of  affinity.  He  contended  that  one 
of  the  main  objects  of  the  chemist  was  to  ascer- 
tain the  nature  of  compounds;  and  thereby  he 
stimulated  the  application  of  analysis  to  chem- 
istry. Boyle  discovered  a  number  of  qualitative 
reactions,  and  applied  them  to  the  detection  of 
substances,  either  free  or  in  combination. 

But  Boyle's  greatest  service  to  learning  con- 
sisted in  the  new  spirit  he  introduced  into  chem- 
istry. Henceforward  chemistry  was  no  longer 
the  mere  helpmeet  of  medicine.  She  became 
an  independent  science,  the  principles  of  which 
were  to  be  ascertained  by  experiment;  a  science 
to  be  studied  with  the  object  of  discovering  the 
laws  regulating  the  phenomena  with  which  it 
is  concerned  —  and  hence  elucidating  truth  for 
truth's  sake.  The  old  philosophy  of  the  Greeks 
had,  as  we  have  seen,  become  merged  into  the 
doctrine  of  the  iatro-chemists;  and  this  was  now 
to  be  purified  from  the  theosophical  mysticism 
with  which  Paracelsus  and  his  followers  had  en- 
shrouded it.  "The  dialectical  subtleties  of  the 
schoolmen  much  more,"  says  Boyle,  "declare 


78  History  of  Chemistry 

the  wit  of  him  that  uses  them  than  increase  the 
knowledge  or  remove  the  doubts  of  sober  lovers 
of  truth For  in  such  speculative  in- 
quiries where  the  naked  knowledge  of  the  truth 
is  the  thing  principally  aimed  at,  what  does  he 
teach  me  worth  thanks,  that  does  not,  if  he  can, 
make  his  notion  intelligible  to  me,  but  by  mys- 
tical terms  and  ambiguous  phrases  darkens  what 
he  should  clear  up,  and  makes  me  add  the  trouble 
of  guessing  at  the  sense  of  what  he  equivocally 
expresses,  to  that  of  learning  the  truth  of  what 
he  seems  to  deliver."  The  influence  of  the  new 
spirit  thus  infused  into  the  science  by  Boyle  is 
seen  in  the  general  style  of  chemical  literature' 
at  the  end  of  the  seventeenth  century,  when  com- 
pared with  that  of  the  close  of  the  sixteenth.  The 
mysticism  and  obscurity  of  the  alchemists  were 
no  longer  tolerated. 

Boyle  was  slender  and  tall,  with  a  countenance 
pale  and  emaciated.  His  constitution  was  del- 
icate and  his  body  feeble,  and  it  was  only  by 
strict  attention  to  diet  and  regularity  of  exercise 
that  he  accomplished  what  he  did.  Although  he 
suffered  occasionally  from  an  excessive  lowness 
of  spirits,  there  was  nothing  morose  or  ascetic  in 
his  nature.  He  was  never  married,  although, 
says  his  friend  John  Evelyn,  "few  men  were 
more  facetious  and  agreeable  in  conversation 
with  the  ladies  whenever  he  happened  to  be 
engaged  among  them." 


"  The  Sceptical  Chemist  "          79 

Kindly,  courteous,  charitable;  unaffected,  and 
temperate  in  his  manner  of  life,  Boyle  enjoyed 
the  respect  and  esteem  of  all  his  contemporaries. 
It  was  said  of  him  that  he  was  never  known  to 
have  offended  any  person  in  his  whole  life  by  any 
part  of  his  deportment.  He  allowed  himself 
a  great  deal  of  decent  cheerfulness,  and  had 
about  him  all  the  tenderness  of  good  nature,  as 
well  as  all  the  softness  of  friendship.  These 
gave  him  a  large  share  of  other  men's  concerns, 
for  he  had  a  quick  sense  of  the  miseries  of  man- 
kind. Although  a  philosopher  in  the  broadest 
sense  of  that  term,  his  peculiar  and  favourite 
study  was  chemistry,  "in  which,"  says  Bishop 
Burnet,  "  he  engaged  with  none  of  those  rave- 
nous and  ambitious  designs  that  drew  many  into 
them.  His  design  was  only  to  find  out  nature, 
to  see  into  what  principles  things  might  be  re- 
solved, and  of  what  they  were  compounded." 

John  Kunkel,  born  in  1630,  was  the  son  of  an 
alchemist  attached  to  the  Court  of  the  Duke  of 
Holstein.  After  serving  his  father  for  some 
years,  he  obtained  employment  as  chemist  and 
pharmacist  under  the  Dukes  Charles  and  Henry, 
of  Lauenburg.  He  subsequently  entered  the 
laboratory  at  Dresden  of  John  George  II.,  Elector 
of  Saxony,  and,  after  teaching  chemistry  at  the 
University  of  Wittenburg,  then  famous  as  a 
medical  school,  he  accepted  an  invitation  to  take 
charge  of  the  glass  works  and  laboratory  of  the 


8o  History  of  Chemistry 

Elector  of  Brandenburg,  at  Berlin.  The  labora- 
tory was  burnt  down,  and  then  Charles  XL  of 
Sweden  called  him  to  Stockholm  and  ennobled 
him  as  Baron  von  Lowenstiern.  He  died  in 
Stockholm  in  1702.  Kunkel's  chief  work  is  his 
Labor atorium  Chymicum,  published  after  his 
death.  It  was  written  in  German.  In  it  Kunkel 
relates  how  he  acquired  possession  of  a  know- 
ledge of  the  manufacture  of  Baldwin's  phos- 
phorus, and  of  the  phosphorus  discovered  by 
Brand  —  perhaps  the  most  important,  as  it 
certainly  was  one  of  the  most  striking,  of  the 
chemical  discoveries  of  the  seventeenth  century. 
Kunkel  did  much  to  liberate  chemical  litera- 
ture from  the  mysticism  and  obscurity  of  al- 
chemy. He  was  scornful  of  the  theories  of 
the  adepts,  and  contemptuous  of  their  tria 
prima. 

I,  old  man  that  I  am,  who  have  been  occupied 
with  chemistry  for  sixty  years,  have  never  yet 
been  able  to  discover  their  fixed  sulphur,  or 
how  it  enters  into  the  composition  of  metals.  .  . 
Moreover,  they  are  not  agreed  among  them- 
selves respecting  the  kind  of  sulphur.  The 
sulphur  of  one  is  not  the  sulphur  of  the  other. 
To  that  one  may  reply  that  each  is  at  liberty 
to  baptise  his  child  as  he  likes.  I  agree:  you 
may  even,  if  you  are  so  disposed,  call  an  ass  a 
cow;  but  you  will  never  make  anyone  believe 
that  your  cow  is  an  ass. 


"The  Sceptical  Chemist "          81 

As  to  the  alkahest  he  says :  — 

There  has  been  much  discussion  concerning 
this  grand  natural  solvent.  Some  derive  it 
from  the  Latin  —  akali  est;  others  from  the 
two  German  words  all  geist  (all  gas) ;  lastly, 
others  say  it  is  from  alles  est  (that's  all).  As 
to  myself,  I  do  not  believe  in  Van  Helmont's 
universal  solvent.  I  call  it  by  its  true  name — • 
alles  Lugen  heist,  or  alles  Lugen  ist  (it  is  all  a  lie). 

Kunkel  discovered  the  secret  of  the  manu- 
facture of  aventurine  glass  and  of  ruby  glass  by 
means  of  the  purple  of  Cassius  —  a  product  from 
gold  first  obtained  by  a  doctor  of  medicine  of  that 
name  in  Hamburg.  He  made  observations  on 
fermentation  and  putrefaction  —  recognised  that 
alum  was  a  double  salt  (salduplicatum) ;  described 
the  present  method  of  repairing  pure  silver,  and 
of  parting  gold  and  silver  by  means  of  sulphuric 
acid.  He  also  described  the  mode  of  preparing 
a  number  of  essential  oils,  detected  the  presence 
of  stearopten  in  oils,  and  discovered  nitrous  ether. 

John  Joachim  Becher,  the  son  of  a  Lutheran 
minister,  was  born  at  Speyer  in  1635.  Owing  to 
the  death  of  his  father  and  the  devastation  of 
the  family  property  during  the  Thirty  Years' 
War,  Becher  had  a  hard  struggle  with  poverty 
during  his  youth,  and  led  a  restless,  wandering 
life.  In  1666  he  was  Professor  of  Medicine  in  the 
University  of  Mayence.  Subsequently  he  went 
to  Munich  as  head  of  the  finest  laboratory  in 


82  History  of  Chemistry 

Europe,  but,  quarrelling  with  the  Chancellor  of 
the  Bavarian  Court,  betook  himself  to  Vienna. 
After  a  short  stay  there,  he  quitted  Austria  for 
Holland,  and  established  himself  in  Haarlem. 
Here  he  proposed  to  the  States-General  to  extract 
gold  from  the  sand-dunes;  but,  the  project  failing, 
he  left  for  England  and  visited  the  Cornish  mines. 
On  the  invitation  of  the  Duke  of  Mecklenburg- 
Giistrow,  he  returned  to  Germany.  Shortly 
afterwards  (in  1682)  he  died,  in  the  forty-seventh 
year  of  his  age.  Becher's  name  is  remembered 
mainly  in  connection  with  his  theory  of  com- 
bustion, which,  as  we  shall  see,  was  subsequently 
developed  by  Stahl  into  the  theory  of  Phlogiston 
—  a  generalisation  which  dominated  chemistry 
until  near  the  close  of  the  eighteenth  century. 

John  Mayow,  born  in  Cornwall  in  1645,  was 
a  practising  physician,  whose  name  chiefly  lives 
by  virtue  of  his  clear  recognition  of  the  sub- 
stance or  principle  in  the  air  which  is  concerned 
in  combustion,  the  calcination  of  metals,  respira- 
tion, and  the  conversion  'of  venous  into  arterial 
blood.  This  substance,  which  he  found  to  be 
contained  in  saltpetre,  he  called  spiritus  igno- 
aereus  or  nitro  aereust.  Mayow  died  at  the  age 
of  thirty-four.  Had  he  been  able  to  follow  up 
his  observations,  he  might  have  influenced  very 
materially  the  development  of  theoretical  chem- 
istry. As  it  was,  he  was  practically  overlooked 
by  his  contemporaries,  and  the  real  significance 


"  The  Sceptical  Chemist "          83 

of  his  work  was  not  appreciated  until  long  after- 
wards. 

Nicolas  Lemery,  also  born  in  1645,  wrote  a 
Cours  de  Chimie,  one  of  the  best  text -books  of 
the  time,  which  passed  through  as  many  as 
thirteen  editions,  and  was  translated  into  English, 
German,  Latin,  Italian,  and  Spanish. 

In  this  book  he  strove,  as  he  says,  to  express 
himself  clearly,  and  to  avoid  the  obscurities 
which  were  to  be  found  in  the  authors  who 
had  preceded  him. 

The  fine  imaginations  of  other  philosophers 
concerning  their  physical  principles  may  elevate 
the  spirit  by  their  grand  ideas,  but  they  prove 
nothing  demonstratively.  And,  as  chemistry 
is  a  science  of  observation,  it  can  only  be  based 
on  what  is  palpable  and  demonstrative. 

Nicolas  Lemery,  who  is  not  to  be  confounded 
with  his  son  Louis,  also  a  chemist,  made  a  consid- 
erable number  of  contributions  to  pharmaceuti- 
cal chemistry;  and  his  Pharmacopee  Universelle, 
Dictionnaire  Universel  des  Drogues  Simples,  and 
Trait'e  de  V Antimoine  were  standard  works  in 
their  day. 

Lemery  was  at  one  time  a  Protestant,  and 
on  the  revocation  of  the  Edict  of  Nantes  fled 
to  England;  but,  embracing  Catholicism,  he  re- 
turned to  Paris,  re-established  his  pharmacy,  and 
was  elected  into  the  Academy  in  1699.  He  died 
in  1715. 


84  History  of  Chemistry 

William  Homberg,  born  in  Batavia  in  1652, 
was  originally  intended  for  the  profession  of  law, 
but,  becoming  attached  to  science,  studied  bot- 
any and  medicine  in  Padua,  chemistry  at  Bolo- 
gna and  in  London,  mechanics  and  optics  at 
Rome,  and  anatomy  at  Leyden.  In  the  course 
of  his  travels  he  visited  the  mines  of  Germany, 
Hungary,  Bohemia,  and  Sweden.  In  1682  he 
was  invited. to  Paris  by  Colbert,  and  in  1691  was 
made  a  member  of  the  Academy  and  was  placed 
by  the  Duke  of  Orleans  in  charge  of  his  laboratory 
—  then  one  of  the  finest  in  Europe.  Homberg 
married  the  daughter  of  Dodart,  the  physician. 
She  became  an  expert  preparateur,  and  was 
of  great  assistance  to  him  in  his  experimental 
inquiries.  He  first  made  known  the  existence 
of  phosphorus  in  France,  discovered  by  Brand, 
of  Hamburg,  and  he  described  the  phosphores- 
cent salt  associated  with  his  name.  He  made 
important  observations  on  the  saturation  of 
alkalis  by  acids,  and  was  aware  that  they  com- 
bined in  different  proportions.  He  was  an  in- 
dustrious worker,  and,  with  the  exception  of 
Cassini,  was  the  most  active  member  of  the 
Academy.  He  died  on  September  24th,  1715. 

Next  to  Boyle,  perhaps  the  most  active  agent 
in  emancipating  chemistry  from  the  yoke  of 
alchemy  was  Boerhaave,  who,  by  his  teaching 
as  Professor  of  Physic,  raised  the  University  of 
Leyden 'to  the  summit  of  its  fame. 


"  The  Sceptical  Chemist "         85 

Hermann  Boerhaave,  the  son  of  a  minister, 
was  born  near  Leyden,  in  1668.  He  occupied  him- 
self in  turn  with  theology,  classics,  mathematics, 
chemistry,  and  botany,  when  he  turned  to  physic, 
and,  after  a  course  of  study  at  the  University 
of  Harderwyk,  in  Gelderland,  began  to  practise. 
In  1702  he  was  appointed  to  a  lectureship,  and 
eventually  to  the  Chair  of  Medicine,  in  the  Uni- 
versity of  Leyden,  of  which  he  became  Rector 
in  1714.  His  reputation  as  a  teacher  spread 
throughout  Europe,  and  steadily  increased  until 
his  death. 

Boerhaave  was  one  of  the  most  learned  men 
of  his  age,  and  singularly  well  cultured,  not  only 
in  science  but  in  history,  poetry,  and  polite  liter- 
ature. He  conversed  in  English,  French,  and 
German,  and  read  Italian  and  Spanish  with  fa- 
cility. "  The  Latin  he  spoke  extempore  in  lec- 
tures or  conversation  was  so  clear  that,  with  his 
action,  method,  and  the  aptness  of  his  similes, 
he  could  level  the  most  abstruse  points  to  the 
meanest  capacities.  "*  He  was  fond  of  music,  and 
a  good  performer  on  several  instruments,  par- 
ticularly the  lute.  He  delighted  to  welcome 
musicians  to  his  house.  His  profession  as  a  phy- 
sician brought  him  wealth,  much  of  which  he 
spent  in  horticulture;  and  the  garden  of  his 
country  seat,  nearly  eight  acres  in  extent, 
was  enriched  with  all  the  exotic  trees  he  could 
1  Burton,  Life  of  Boerhaave  p.  58  et  seq. 


After  a  painting  by  T.  Wandelaar 


"  The  Sceptical  Chemist  "         87 

procure  and  induce  to  flourish  in  the  climate  of 
Holland. 

Boerhaave  was  of  a  robust  frame  and  healthy 
constitution,  early  inured  to  constant  exercise 
and  the  inclemencies  of  weather.  His  stature 
was  rather  tall,  and  his  habit  corpulent.  He  had  a 
large  head,  short  neck,  florid  complexion,  light 
brown  curled  hair  (for  he  did  not  wear  a  wig),  an 
open  countenance,  and  resembled  Socrates  in 
the  flatness  of  his  nose  and  his  natural  urbanity. 
He  died  at  Leyden  on  September  23rd,  1738,  in 
the  seventieth  year  of  his  age. 

As  a  chemist  Boerhaave  is  chiefly  known  by 
his  Elementa  Chemia,  published  in  1732  — the 
most  complete  and  most  luminous  chemical 
treatise  of  its  time,  translations  of  which  appeared 
in  the  chief  European  languages.  The  work  is 
divided  into  three  main  parts.  The  first  is 
concerned  with  the  origin  and  progress  of  the  art, 
and  with  the  personal  history  of  its  most  dis- 
tinguished cultivators.  The  second  and  largest 
part  deals  with  the  attempt  to  form  a  system  of 
chemistry  based  on  such  observational  matter 
as  seemed  well  established.  The  third  consists 
of  a  collection  of  chemical  processes  relating  to 
the  analysis  or  decomposition  of  bodies,  grouped 
under  the  heads  of  "  vegetables,"  "animals, " 
and  "fossils"  -the  beginnings,  in  fact,  of  sub- 
division of  the  science  into  organic  and  inor- 
ganic chemistry. 


88  History  of  Chemistry 

As  regards  his  belief  in  alchemy,  Boerhaave 
was  an  agnostic :  he  neither  affirmed  nor  denied 
the  possibility  of  transmutation.  In  this  re- 
spect he  resembled  Newton  and  Boyle.  Boyle, 
indeed,  was  singularly  cautious  and  reticent  in 
his  references  to  alchemistic  matters.  As  was 
said  of  him  by  Shaw,  he  was  too  wise  to  set  any 
bounds  to  nature:  he  was  not  prone  to  say  that 
every  strange  thing  must  needs  be  impossible, 
for  he  saw  strange  things  every  day,  and  was 
well  aware  that  there  are  powerful  forces  in  the 
world  of  whose  laws  and  modes  of  action  he 
knew  nothing.  With  that  wariness  which  was 
habitual  to  him,  he  was  wont  to  say  that  "  those 
who  had  seen  them  might  better  believe  them 
than  those  who  had  not";  and  he  was  modest 
enough  to  suppose  that  Paracelsus  or  Helmont 
might  conceivably  know  of  agents  of  which  he 
was  ignorant. 

Boerhaave  unquestionably  spent  much  time 
in  the  study  of  alchemical  works,  particularly 
those  of  Paracelsus  and  Helmont,  which  he  re- 
peatedly read.  The  Philosophical  Transactions 
of  the  Royal  Society  contain  the  results  of  a 
laborious  but  fruitless  investigation  by  him  on 
quicksilver,  which  he  undertook  in  the  hope  of 
discovering  the  seminal  or  engendering  matter 
which,  on  the  old  theory  of  the  generation  of 
metals,  was  supposed  to  be  contained  in  mercury. 
But  although,  as  he  relates,  he  tortured  it  by 


"  The  Sceptical  Chemist  "         89 

"  conquassation,  trituration,  digestion,  and  by 
distillation,  either  alone  or  amalgamated  with 
lead,  tin,  or  gold,  repeating  this  operation  to 
511  or  even  to  877  distillations,"  the  mercury 
appeared  only  "  rather  more  bright  and  liquid, 
without  any  other  variation  in  its  form  or  virtues, 
and  acquired  very  little,  if  any,  increase  of  its 
specific  gravity." 

Stephen  Hales  (167 7- 1761), an  ingenious  divine 

—  he   held  the   perpetual    curacy    of    Tedding- 
ton,  and  lived  practically  the  greater  part  of  his 
life  there  —  distinguished  as  a  physiologist  and 
inventor,  occupied  himself  in  chemical  pursuits, 
and  made  a  number  of  observations  on  the  pro- 
duction of  gaseous  substances.     His  results  were 
communicated  to  the  Royal  Society  and  subse- 
quently republished,  in  a  collected  form,  under 
the  title  of  Statical  Essays.    In  these  experiments 
he  used  methods  very  similar  in  principle  to  those 
subsequently  employed  by  Priestley.     It  is  evi- 
dent from  his  description  of  his  experiments  that 
he  must  have  prepared  a  considerable  number  of 
gaseous  substances  —  hydrogen,   carbonic  acid, 
carbonic  oxide,  sulphur  dioxide,  marsh  gas,  etc. 

—  but  he  seems  to  have   made   no   systematic 
attempt  to  study  their  properties,  as  he  consid- 
ered  that    they  were    simply  air,   modified    or 
"  tinctured"  by  the  presence  of  substances  which 
he  regarded  as  more  or  less  fortuitous.     Prior 
to  the  time  of  Black  all  forms  of  gaseous  sub- 


go  History  of  Chemistry 

stance  were  regarded  as  substantially  identical 
—  in  fact,  as  being  air,  as  understood  by  the 
Ancients  —  a  simple  elementary  substance.  It 
was  Black's  study  of  carbonic  acid  which  first 
clearly  established  that  there  were  essentially 
distinct  varieties  of  gaseous  matter. 


CHAPTER   VII 
PHLOGISTONISM 

CVEN  before  the  appearance  of  The  Sceptical 
*^  Chemist  there  was  a  growing  conviction  that 
the  old  hypotheses  as  to  the  essential  nature  of 
matter  were  inadequate  and  misleading.  We 
have  seen  how  the  four  ''elements"  of  the  Peripa- 
tetics had  become  merged  into  the  tria  prima  — 
the  "salt,"  "sulphur,"  and  "mercury"  —  of  the 
Paracelsians.  As  the  phenomena  of  chemical 
action  became  better  known,  the  latter  iatro- 
chemists — or,  rather,  that  section  of  them  which 
recognised  that  chemistry  had  wider  aims  than 
to  minister  merely  to  medicine  —  felt  that  the 
conception  of  the  tria  prima,  as  understood  by 
Paracelsus  and  his  followers,  was  incapable  of 
being  generalised  into  a  theory  of  chemistry. 
Becher,  while  clinging  to  the  conception  of  three 
primordial  substances  as  making  up  all  forms  of 
matter,  changed  the  qualities  hitherto  associated 
with  them.  According  to  the  new  theory,  all 
matter  was  composed  of  a  mercurial,  a  vitreous, 
and  a  combustible  substance  or  principle,  in 
varying  proportions,  depending  upon  the  nature 
of  the  particular  form  of  matter.  When  a  body 
was  burnt  or-  a  metal  calcined,  the  combustible 


92  History  of  Chemistry 

substance  —  the     terra    pinguis    of    Becher  — 
escaped. 

This  attempt  to  connect  the  phenomena  of 
combustion  and  calcination  with  the  general 
phenomena  of  chemistry  was  still  further  devel- 
oped by  Stahl,  and  was  eventually  extended 
into  a  comprehensive  theory  of  chemistry,  which 
was  fairly  satisfactory  so  long  as  no  effort  was 
made  to  test  its  sufficiency  by  an  appeal  to  the 
balance. 

George  Ernest  Stahl,  who  developed  Becher's 
notion  into  the  theory  of  phlogiston  (<£Aoyiords  — 
burnt),  and  thereby  created  a  generalisation 
which  first  made  chemistry  a  science,  was  born  at 
Anspach  in  1660,  became  Professor  of  Medicine 
and  Chemistry  at  Halle  in  1693,  physician  to 
the  King  of  Prussia  in  1716,  and  died  in  Berlin 
in  1734. 

Stahl  contributed  little  or  nothing  to  practical 
chemistry ;  and  no  new  fact  or  discovery  is  asso- 
ciated with  his  name.  His  service  to  science  con- 
sists in  the  temporary  success  he  achieved  in 
grouping  chemical  phenomena,  and  in  explaining 
them  consistently  by  a  comprehensive  hypoth- 
esis. 

The  theory  of  phlogiston  was  originally 
broached  as  a  theory  of  combustion.  According 
to  this  theory,  bodies  such  as  coal,  charcoal, 
wood,  oil,  fat,  etc.,  burn  because  they  contain  a 
combustible  principle,  which  was  assumed  to  be 


Phlogistonism  93 

a  material  substance  and  uniform  in  character. 
This  substance  was  known  as  phlogiston.  All 
combustible  bodies  were  to  be  regarded,  therefore, 
as  compounds,  one  of  their  constituents  being 
phlogiston:  their  different  natures  depended 
partly  upon  the  proportion  of  phlogiston  they 
contain,  and  partly  upon  the  nature  and  amount 
of  their  other  constituents.  A  body,  when 
burning,  was  parting  with  its  phlogiston;  and 
all  the  phenomena  of  combustion  —  the  flame, 
heat,  and  light — were  caused  by  the  violence 
of  the  expulsion  of  that  substance.  Certain 
metals  —  as,  for  example,  zinc  —  could  be 
caused  to  burn,  and  thereby  to  yield  earthy 
substances,  sometimes  white  in  colour,  at  other 
times  variously  coloured.  These  earthy  sub- 
stances were  called  calces,  from  their  general 
resemblance  to  lime.  Other  metals,  like  lead 
and  mercury,  did  not  appear  to  burn;  but  on 
heating  them  they  gradually  lost  their  metallic 
appearance,  and  became  converted  into  calces. 
This  operation  was  known  as  calcination.  In 
the  act  of  burning  or  of  calcination  pholgiston 
was  expelled.  Hence  metals  were  essentially 
compound:  they  consisted  of  phlogiston  and  a 
calx,  the  nature  of  which  determined  the  char- 
acter of  the  metal.  By  adding  phlogiston  to  a 
calx  the  metal  was  regenerated.  Thus,  on 
heating  the  calx  of  zinc  or  of  lead  with  coal,  or 
charcoal,  or  wood,  metallic  zinc  or  lead  was 


94  History  of  Chemistry 

again  formed.  When  a  candle  burns,  its  phlo- 
giston is  transferred  to  the  air;  if  burned  in  a 
limited  supply  of  air,  combustion  ceases,  because 
the  air  becomes  saturated  with  phlogiston. 

Respiration  is  a  kind  of  combustion  whereby 
the  temperature  of  the  body  is  maintained.  It 
consists  simply  in  the  transference  of  the  phlo- 
giston of  the  body  to  the  air.  If  we  attempt 
to  breathe  in  a  confined  space,  the  air  becomes 
eventually  saturated  with  the  phlogiston,  and 
respiration  stops.  The  various  manifestations 
of  chemical  action,  in  like  manner,  were  attrib- 
uted to  this  passing  to  and  fro  of  phlogiston. 
The  colour  of  a  substance  is  connected  with  the 
amount  of  phlogiston  it  contains.  Thus,  when 
lead  is  heated,  it  yields  a  yellow  substance  (lith- 
arge) ;  when  still  further  heated,  it  yields  a  red 
substance  (red  lead).  These  differences  in 
colour  were  supposed  to  depend  upon  the  varying 
amount  of  phlogiston  expelled. 

The  doctrine  of  phlogiston  was  embraced  by 
nearly  all  Stahl's  German  contemporaries,  no- 
tably by  Marggraf,  Neumann,  Eller,  and  Pott. 
It  spread  into  Sweden,  and  was  accepted  by 
Bergman  and  Scheele;  into  France,  where  it 
vvas  taught  by  Duhamel,  Rouelle,  and  Macquer; 
and  into  Great  Britain,  where  its  most  influential 
supporters  were  Priestley  and  Cavendish.  It 
continued  to  be  the  orthodox  faith  until  the  last 
quarter  of  the  eighteenth  century,  when,  after 


Phlogistonism  95 

the  discovery  of  oxygen,  it  was  overturned  by 
Lavoisier. 

During  the  sway  of  phlogiston  chemistry  made 
many  notable  advances  —  not  by  its  aid,  but 
rather  in  spite  of  it.  As  a  matter  of  fact,  until 
the  time  of  Lavoisier  few,  if  any,  investigations 
were  made  with  the  express  intention  of  testing 
it,  or  of  establishing  its  sufficiency.  When  new' 
phenomena  were  observed  the  attempt  was  no 
doubt  made  to  explain  them  by  its  aid,  fre- 
quently with  no  satisfactory  result.  Indeed, 
even  in  the  time  of  Stahl,  facts  were  known 
which  it  was  difficult  or  impossible  to  reconcile 
with  his  doctrine;  but  these  were  either  ignored, 
or  their  true  import  explained  away.  Although, 
therefore,  these  advances  were  in  no  way  con- 
nected with  phlogiston,  it  will  be  convenient  to 
deal  with  the  more  important  of  them  now, 
inasmuch  as  they  were  made  during  the  phlo- 
gistic period. 

With  the  exception  of  Marggraf,  Stahl's 
German  contemporaries  contributed  few  facts  of 
first-rate  importance  to  chemistry.  Pott,  who 
was  born  at  Halberstadt  in  1692  and  become 
Professor  of  Chemistry  in  Berlin  in  1737,  is 
chiefly  remembered  by  his  work  on  porcelain, 
the  chemical  nature  and  mode  of  origin  of  which 
he  first  elucidated.  Marggraf,  born  in  Berlin 
in  1709,  was  one  of  the  best  analysts  of  his  age. 
He  first  clearly  distinguished  between  lime  and 


96  History  of  Chemistry 

alumina,  and  was  one  of  the  earliest  to  point  out 
that  the  vegetable  alkali  (potash)  differed  from 
the  mineral  alkali  (soda).  He  also  showed  that 
gypsum,  heavy  spar,  and  potassium  sulphate 
were  analogous  in  composition.  He  clearly 
indicated  the  relation  of  phosphoric  acid  to 
phosphorus,  described  a  number  of  methods  of 
preparing  that  acid,  and  explained  the  origin  of 
the  phosphoric  acid  in  urine. 

Of  the  Swedish  chemists  of  that  period,  the 
most  notable  was  Scheele. 

Carl  Wilhelm  Scheele  was  born  in  1742  at 
Stralsund.  When  fourteen  years  of  age  he  was 
apprenticed  to  an  apothecary  at  Gothenburg, 
and  began  the  study  of  experimental  chemistry, 
which  he  continued  to  prosecute  as  an  apothe- 
cary at  Malmo,  Stockholm,  Upsala,  and  eventu- 
ally at  Koping  on  Lake  Malar,  where  he  died  in 
1786,  in  the  forty-third  year  of  his  age.  During 
the  comparatively  short  period  of  his  scientific 
activity  Scheele  made  himself  the  greatest 
chemical  discoverer  of  his  time. 

He  first  isolated  chlorine,  and  determined  the 
individuality  of  manganese  and  baryta.  He 
was  an  independent  discoverer  of  oxygen, 
ammonia,  and  hydrogen  chloride.  He  discov- 
ered also  hydrofluoric,  nitro-sulphonic,  molybdic, 
tungstic,  and  arsenic,  among  the  inorganic  acids; 
and  lactic,  gallic,  pyrogallic,  oxalic,  citric,  tar- 
taric,  malic,  mucic,  and  uric  acids  among  the 


Phlogistonism 


97 


CARL  WILHELM  SCHEELE. 

From  the  statue  by  Borjeson  at  Stockholm. 

organic  acids.  He  isolated  glycerine  and  milk- 
sugar;  determined  the  nature  of  microcosmic 
salt,  borax,  and  Prussian  blue,  and  prepared 
hydrocyanic  acid.  He  demonstrated  that 
graphite  is  a  form  of  carbon.  He  discovered 
the  chemical  nature  of  sulphuretted  hydrogen, 
arsenuretted  hydrogen,  and  the  green  arsenical 


98  History  of  Chemistry 

pigment  known  by  his  name.  He  invented  new 
processes  for  preparing  ether,  powder  of  algaroth, 
phosphorus,  calomel,  and  magnesia  alba.  He 
first  prepared  ferrous  ammonium  sulphate, 
showed  how  iron  may  be  analytically  separated 
from  manganese;  and  described  the  method  of 
breaking  up  mineral  silicates  by  fusion  with 
alkaline  carbonates.  Scheele's  contributions  to 
chemical  theory  were  slight  and  unimportant, 
but  as  a  discoverer  he  stands  pre-eminent. 

Of  the  French  phlogistians  we  have  space  only 
to  mention  Duhamel  and  Macquer. 

Henry  Louis  Duhamel  du  Monceau  was  born 
at  Paris  in  1700.  He  was  one  of  the  earliest 
to  make  experiments  on  ossification,  and  one  of 
the  first  to  detect  the  difference  between  potash 
and  soda. 

Peter  Joseph  Macquer  was  born  in  1718  at 
Paris.  He  investigated  the  nature  of  Prussian 
blue  (discovered  by  Diesbach,  of  Berlin,  in  1710), 
worked  on  platinum,  wrote  one  of  the  best  text- 
books of  his  time,  published  a  dictionary  of 
chemistry,  and  was  an  authority  of  the  chemistry 
of  dyeing. 

In  addition  to  those  already  mentioned,  the 
most  notable  names  as  workers  in  chemistry  in 
Great  Britain  during  the  eighteenth  century  are 
Black,  Priestley,  and  Cavendish. 

Joseph  Black  was  born  in  1728  at  Bordeaux, 
where  his  father  was  engaged  in  the  wine  trade. 


Phlogistonism  99 

A  student  of  the  University  of  Glasgow,  he 
became  its  Professor  of  Chemistry  in  1756.  In 
1766  he  was  transferred  to  the  Chemical  Chair 
of  the  University  of  Edinburgh,  and  died  in  1799. 
Black  published  only  three  papers,  the  most 
important  of  which  is  entitled  Experiments  upon 
Magnesia  Alba,  Quicklime,  and  Other  Alkaline 
Substances.  He  proved  that  magnesia  is  a 
peculiar  earth  differing  in  properties  from  lime. 
Lime  is  a  pure  earth,  while  limestone  is  carbonate 
of  lime.  He  showed  that  magnesia  will  also 
combine  with  carbonic  acid,  and  he  explained 
that  the  difference  between  the  mild  and  caustic 
alkalis  is  that  the  former  contain  carbonic  acid, 
whereas  the  latter  do  not.  He  also  explained 
how  lime  is  able  to  convert  the  mild  alkalis  into 
caustic  alkalis.  Simple  and  well  known  as  these 
facts  are  to-day,  their  discovery  in  1755  excited 
great  interest,  and  marked  an  epoch  in  the 
history  of  chemistry.  Black's  name  is  asso- 
ciated with  the  discovery  of  latent  and  specific 
heat,  and  he  made  the  first  determinations  of  the 
amount  of  heat  required  to  convert  ice  into 
water. 

Joseph  Priestley,  the  son  of  a  clothdresser, 
was  born  in  1733  at  Fieldhead,  near  Leeds. 
When  seven  years  of  age,  on  the  death  of  his 
mother,  he  was  taken  charge  of  by  his  aunt,  and 
was  educated  for  the  Nonconformist  ministry, 
eventually  becoming  a  Unitarian.  He  was  first 


JOSEPH  PRIESTLEY. 

From  a  mezzotint  after  Fuseli  in  the  possession  of  the  Royal  Society. 


Phlogistonism  101 

attracted  to  science  by  the  study  of  electricity, 
of  which  he  compiled  a  history.  At  Leeds, 
where  he  had  charge  of  the  Mill  Hill  congrega- 
tion, he  turned  his  attention  to  chemistry, 
mainly  from  the  circumstance  that  he  lived  near 
a  brewery  and  had  the  opportunity  of  procuring 
large  quantities  of  carbonic  acid,  the  properties 
of  which  he  carefully  studied.  He  abandoned 
the  ministry  for  a  time  to  become  librarian  and 
literary  companion  to  Lord  Shelburne,  with 
whom  he  remained  seven  years.  During  this 
time  he  industriously  pursued  chemical  inquiry, 
and  discovered  a  large  number  of  aeriform 
bodies  —  viz.,  nitric  oxide,  hydrogen  chloride, 
sulphur  dioxide,  silicon  fluoride,  ammonia, 
nitrous  oxide,  and,  most  important  of  all  from 
the  point  of  view  of  chemical  theory,  oxygen  gas. 
Priestley's  work  gave  a  remarkable  impetus  to 
the  study  of  pneumatic  chemistry.  It  exercised 
great  influence  on  the  extension  of  chemical 
science,  and  —  in  other  hands  than  his  —  on  the 
development  of  chemical  theory.  The  most 
important  of  his  contributions  to  science  are 
contained  in  his  Experiments  and  Observations 
on  Different  Kinds  of  Air.  This  work  not  only 
gives  an  account  of  the  methods  by  which  he 
isolated  the  gases  he  discovered,  but  describes 
a  great  number  of  incidental  observations,  such 
as  the  action  of  vegetation  on  respired  air, 
showing  that  the  green  parts  of  p\plE]$¥Ufe&fg&* 

f  OF   TH€    " 

I   UNIVERSITY   ) 

OF 


102  History  of  Chemistry 

in  sunlight  to  decompose  carbonic  acid  and  to 
restore  oxygen  to  the  atmosphere.  He  was,  in 
fact,  one  of  the  earliest  to  trace  the  specific 
action  of  animals  and  plants  on  atmospheric  air, 
and  to  show  how  these  specific  actions  main- 
tained its  purity  and  constancy  of  composition. 
He  initiated  the  art  of  eudiometry  (gas  analysis), 
and  was  the  first  to  establish  that  the  air  is  not 
a  simple  substance,  as  imagined  by  the  ancients. 
Priestley  is  to  be  credited  with  the  invention  of 
soda-water,  which  he  prepared  as  a  remedy  for 
scurvy;  and  his  name  is  connected  with  the 
so-called  pneumatic  trough  —  a  simple  enough 
piece  of  apparatus,  but  one  which  proved  to  be 
of  the  greatest  service  to  him  in  his  inquiries. 

After  leaving  Lord  Shelburne,  Priestley  re- 
moved to  Birmingham  and  resumed  his  ministry. 
His  religious  and  political  opinions  made  him 
obnoxious  to  the  Church  and  State  party;  and 
during  the  riots  of  1791  his  house  was  wrecked, 
his  books  and  apparatus  destroyed,  and  his 
life  endangered.  Eventually  he  emigrated  to 
America,  and  settled  at  Northumberland,  where 
he  died  on  February  6th,  1804,  in  the  seventy- 
first  year  of  his  age. 

Henry  Cavendish  was  born  at  Nice  in  1731, 
and  died  in  London  in  1810.  He  was  a  natural 
philosopher  in  the  widest  sense  of  that  term, 
and  occupied  himself  in  turn  with  nearly  every 
branch  of  physical  science.  He  was  a  capable 


From  a  drawing  by  Alexander  in  the  Print  Room  of  the  British  Museum. 


104  History  of  Chemistry 

astronomer  and  an  excellent  mathematician, 
and  he  was  one  of  the  earliest  to  work  on  the 
subject  of  specific  heat,  and  to  improve  the 
thermometer  and  the  methods  of  making  ther- 
mometric  observations.  He  also  determined  the 
mean  density  of  the  earth.  He  made  accurate 
observations  on  the  properties  of  carbonic  acid 
and  hydrogen,  greatly  improved  the  methods  of 
eudiometry,  and  first  established  the  practical 
uniformity  of  the  composition  of  atmospheric  air. 
His  greatest  discovery,  however,  was  his  deter- 
mination of  the  composition  of  water.  He  was 
the  first  to  prove  that  water  is  not  a  simple  or 
elementary  substance,  as  supposed  by  the 
ancients,  but  is  a  compound  of  hydrogen  and 
oxygen.  In  certain  of  his  trials  he  found  that 
the  water  formed  by  the  union  of  oxygen  and 
hydrogen  was  acid  to  the  taste ;  and  the  search 
for  the  cause  of  this  acidity  led  him  to  the  dis- 
covery of  the  composition  of  nitric  acid.  He 
was  the  first  to  make  a  fairly  accurate  analysis 
of  a  natural  water,  and  to  explain  what  is  known 
as  the  hardness  of  water. 

Phlogistonism  may  be  said  to  have  dominated 
chemistry  during  three-fourths  of  the  eighteenth 
century.  Although  radically  false  as  a  concep- 
tion and  of  little  use  in  the  true  interpretation  of 
chemical  phenomena,  it  cannot  be  said  to  have 
actually  retarded  the  pursuit  of  chemistry. 
Men  went  on  working  and  accumulating  chemical 


Phlogistonism  105 

facts  uninspired  and,  for  the  most  part,  unin- 
fluenced by  it.  Even  Priestley,  perhaps  one  of 
the  most  conservative  of  the  followers  of  Stahl, 
regarded  his  dogma  with  a  complacent  toler- 
ance ;  and  as  its  inconsistencies  became  apparent 
he  was  more  than  once  on  the  point  of  renouncing 
it.  Of  one  thing  he  was  quite  convinced,  and 
that  was  that  Stahl  had  greatly  erred  in  his 
conception  of  the  real  nature  of  phlogiston. 
Perhaps  the  most  signal  disservice  which 
phlogiston  did  to  chemistry  was  to  delay  the 
general  recognition  of  Boyle's  views  of  the  nature 
of  the  elements.  The  alchemists,  it  will  be 
remembered,  regarded  the  metals  as  essentially 
compound.  Boyle  was  disposed  to  believe  that 
they  were  simple.  Becher  and  Stahl  and  their 
followers,  until  the  last  quarter  of  the  eighteenth 
century,  also  regarded  them  as  compounds, 
phlogiston  being  one  of  their  constituents.  On 
the  other  hand,  what  we  now  know  to  be  com- 
pounds -—such  as  the  calces,  the  acids,  and 
water  itself  —  were  held*  by  the  phlogistians  to 
be  simple  substances. 

The  discovery,  in  1774,  of  oxygen  —  the 
dephlogisticated  air  of  Priestley  —  and  the 
recognition  of  the  part  it  plays  in  the  phenomena 
which  phlogiston  was  invoked  to  explain,  mark 
the  termination  of  one  era  in  chemical  history 
and  the  beginning  of  another.  Before  entering 
upon  an  account  of  the  new  era  it  is  desirable 


io6  History  of  Chemistry 

to  take  stock  of  the  actual  condition  of  chemical 
knowledge  at  the  end  of  the  phlogistic  period, 
and  to  show  what  advances  had  been  made  in 
pure  and  applied  chemistry  during  that  time. 

During  the  eighteenth  century  greater  insight 
was  gained  into  the  operations  of  the  form  of 
energy  with  which  chemistry  is  mainly  con- 
cerned, and  views  concerning  chemical  affinity 
and  its  causes  began  to  assume  more  definite 
shape,  chiefly  owing  to  the  labours  of  Boerhaave, 
Bergman,  Geoff roy,  and  Rouelle.  It  was  clearly 
recognised  that  the  large  group  of  substances 
comprised  under  the  term  "  salts"  were  com- 
pound, and  made  up  of  two  contrasted  and,  in  a 
sense,  antagonistic  constituents,  classed  gener- 
ically  as  acids  and  bases. 

On  the  practical  side  chemistry  made  consid- 
erable progress.  Analysis  —  a  term  originally 
applied  by  Boyle  -—  greatly  advanced.  It  was, 
of  course,  mainly  qualitative;  but,  thanks  to 
the  labours  of  Boyle,  Hoffmann,  Marggraf, 
Scheele,  Bergman,  Gahn,  and  Cronstedt,  certain 
reactions  and  reagents  came  to  be  systemati- 
cally applied  to  the  recognition  of  chemical  sub- 
stances, and  the  precision  with  which  these 
reagents  were  used  led  to  the  detection  of 
hitherto  unknown  elements.  The  beginnings 
of  a  quantitative  analysis  were  made  even  be- 
fore the  time  of  Boyle,  but  its  principles  were 
greatly  developed  by  him,  and  were  further 


Phlogistonism  107 

extended  by  Homberg,  Marggraf,  and  Bergman. 
Marggraf  accurately  determined  the  amount  of 
silver  chloride  formed  by  adding  common  salt 
to  a  solution  of  a  known  weight  of  silver,  and 
Bergman  first  pointed  out  that  estimations  of 
substances  might  be  conveniently  made  by 
weighing  them  in  the  form  of  suitably  prepared 
compounds,  which,  it  was  implicitly  assumed, 
were  of  uniform  and  constant  composition. 
The  foundations  of  an  accurate  system  of  gaseous 
analysis  were  made  by  Cavendish;  and  various 
forms  of  physical  apparatus  were  applied  to  the 
service  of  chemistry. 

To  the  elements  which  were  known  prior  to 
Boyle's  time,  although  not  recognised  as  such, 
there  were  added  phosphorus  (Brand,  1669), 
nitrogen  (Rutherford),  chlorine  (Scheele,  1774), 
manganese  (Gahn,  1774),  cobalt  (Brandt,  1742), 
nickel  (Cronstedt,  17 50),  and  platinum  (Watson, 
1750).  Baryta  was  discovered  by  Scheele,  and 
strontia  by  Crawford.  Phosphoric  acid  was 
discovered  by  Boyle,  and  its  true  nature  deter- 
mined by  Marggraf;  Cavendish  first  made 
known  the  composition  of  nitric  acid.  As 
already  stated,  Scheele  first  isolated  molybdic 
and  tungstic  acids  and  determined  the  existence 
of  a  number  of  the  organic  acids  (p.  75).  Other 
discoveries  —  such  as  the  true  nature  of  lime-, 
stone  and  magnesia  alba  and  their  relations 
respectively  to  lime  and  magnesia  by  Black,  the 


io8  History  of  Chemistry 

many  gaseous  substances  by  Priestley,  and  the 
compound   nature    of    water    by    Cavendish  — 
have  already  been  referred  to. 

Technical  chemistry  also  greatly  developed 
during  the  eighteenth  century,  thanks  to  the 
efforts  of  Gahn,  Marggraf,  Duhamel,  Reaumur, 
Macquer,  Kunkel,  and  Hellot;  and  many  import- 
ant industrial  processes  —  such  as  the  manu- 
facture of  sulphuric  acid  by  Ward  of  Richmond, 
and  subsequently  by  Roebuck  at  Birmingham, 
and  the  Leblanc  process  of  conversion  of  com- 
mon salt  into  alkali  —  had  their  origin  during 
this  period. 


CHAPTER  VIII 
LAVOISIER  AND  LA  REVOLUTION  CHIMIQUE 

\17E  have  seen  how  chemistry  made  a  new  de- 
*  ^  parture  during  the  political  upheaval  which 
occurred  in  this  country  about  the  middle  of  the 
seventeenth  century.  It  acquired  a  new  im- 
petus and  took  a  fresh  course  during  the  politi- 
cal cataclysm  which  overwhelmed  France  and 
alarmed  Europe  towards  the  close  of  the 
eighteenth  century.  The  instigator  and  leader 
of  this  second  revolution  in  chemistry  was 
Lavoisier,  one  of  the  most  distinguished  men 
of  his  age,  and  himself  a  victim  of  the  political 
fury  of  his  own  people. 

Antoine-Laurent  Lavoisier  was  born  in 
Paris  in  1743.  At  the  Jardin  du  Roi  he  came 
under  the  influence  of  Rouelle,  one  of  the  best 
teachers  of  his  time,  who  eventually  shaped  his 
career  as  a  chemist.  In  1765  he  sent  to  the 
Academy  his  first  paper  on  gypsum,  which  is 
noteworthy  as  giving  for  the  first  time  the  true 
explanation  of  the  "setting"  of  plaster  of  Paris, 
and  the  reason  -why  overburnt  gypsum  will  not 
re  hydrate.  Three  years  later  he  became  a  mem- 
ber of  the  Fer  me -general  —  a  company  of  finan- 
ciers to  whom  the  State  conceded,  for  a  fixed 
109 


no  History  of  Chemistry 

annual  sum,  the  right  of  collecting  the  indirect 
taxes  of  the  country.  It  was  this  connection 
that  brought  Lavoisier  to  the  scaffold  during 
the  revolution  of  1794.  Like  Stahl,  Lavoisier 
discovered  no  new  substance;  but,  also  like  Stahl, 
he  created  a  new  epoch  by  destroying  the  philo- 
sophical system  which  Stahl  had  established. 

It  is  commonly  stated  that  the  exception  is 
a  proof  of  the  rule.  The  history  of  science  can 
show  many  instances  whereby  the  rule  has  been 
demolished  by  the  exception.  Little  facts  have 
killed  big  theories,  even  as  a  pebble  has  slain  a 
giant.  During  the  reign  of  phlogiston  a  few  of 
such  facts  were  not  unknown  —  at  least  to  some 
of  the  better  informed  of  Stahl' s  followers. 

Some  of  the  alchemists  had  discovered  that  a 
metal  gained,  not  lost,  weight  by  calcination.  This 
was  known  as  far  back  as  the  sixteenth  century. 
It  had  been  pointed  out  by  Cardan  and  by  Liba- 
vius.  Sulzbach  showed  that  such  was  the  case 
with  mercury.  Boyle  proved  it  in  the  case  of 
tin,  and  Rey  in  that  of  lead.  Moreover,  as 
knowledge  increased  it  became  certain  that 
Stahl's  original  conception  of  the  principle  of 
combustion  as  a  ponderable  substance  —  he 
imagined,  with  Becher,  that  it  was  of  the  nature 
of  an  earth  —  was  not  tenable.  The  later 
phlogistians  were  disposed  to  regard  it  as  prob- 
ably identical  with  hydrogen.  But  even  hydro- 
gen has  weight,  and  facts  seemed  to  require 


La  Revolution  Chimique        in 

that  phlogiston,  if  it  existed  at  all,   should  be 
devoid  of  weight. 

Towards  the  latter  half  of  the  eighteenth  cen- 
tury clearer  views  began  to  be  held  concerning 
the  relations  of  atmospheric  air  to  the  phenom- 
ena of  combustion  and  of  calcination;  many 
half-forgotten  facts  relating  to  these  phenomena 
were  recalled,  and  the  inconsistencies  and  in- 
sufficiency of  phlogiston  as  a  dogma  became 
gradually  manifest.  Three  cardinal  facts  con- 
spired to  bring  about  its  overthrow  —  the  iso- 
lation of  oxygen  by  Priestley;  the  recognition 
by  him  of  the  nature  of  atmospheric  air,  and  of 
the  fact  that  one  of  its  constituents  is  oxygen; 
and,  lastly,  the  discovery  by  Cavendish  that 
water  is  a  compound,  and  that  its  constituents 
are  oxygen  and  hydrogen.  The  significance  of 
these  facts  was  first  clearly  grasped  by  Lavoisier, 
and  to  him  is  due  the  credit  of  their  true  inter- 
pretation. By  reasoning  and  experiment  he 
proved  conclusively  that  all  ordinary  phenom- 
ena of  burning  are  so  many  instances  of  the 
combination  of  the  oxygen  of  the  air  with  the 
combustible  substance ;  that  calcination  is  a  pro- 
cess of  combination  of  the  oxygen  in  the  air  with 
the  metal,  which  thereby  increases  in  weight  by 
the  amount  of  oxygen  combined.  Water  — 
no  longer  a  simple  substance  —  is  formed  by 
the  union,  weight  for  weight,  of  oxygen  and 
hydrogen.  Lavoisier's  reasoning  was  so  sound 


ii2  History  of  Chemistry 

and  his  experimental  evidence  so  complete  that 
his  views  gradually  gained  acceptance  in  France. 
The  phlogiston  myth  was  thus  exploded.  In- 
spired by  Lavoisier,  a  small  band  of  French 
chemists  —  Berthollet,  Fourcroy,  Guyton  de 
Morveau  — -  thereupon  set  to  work  to  remodel 
the  system  of  chemistry  and  to  recast  its 
nomenclature  so  as  to  eliminate  all  reference 
to  phlogiston.  The  very  names  "  oxygen,"  "  hy- 
drogen," " nitrogen,"  corresponding  respectively 
.to  the  "  dephlogisticated  air,"  "phlogiston,  "  and 
" phlogisticated  air"  of  Priestley,  were  coined 
by  the  new  French  school.  For  a  time  le  prin- 
cipe  oxygine  was  regarded  by  this  school  in  much 
the  same  relation  as  phlogiston  was  regarded  by 
Stahl  and  his  followers.  The  one  fetich  was 
exchanged  for  the  other.  The  combustible 
principle  — phlogiston  —  was  renounced  for  the 
acidifying  principle  —  oxygen.  The  new  chem- 
istry for  a  time  centred  itself  round  oxygen,  just 
as  the  old  chemistry  had  centred  itself  round 
phlogiston.  The  views  of  the  French  school  met 
with  no  immediate  acceptance  in  Germany,  the 
home  of  phlogistonism,  or  in  Sweden  or  England, 
possibly  owing,  to  some  extent,  to  national  preju- 
dices. The  spirit  of  revolution,  even  although 
it  might  be  an  intellectual  revolution,  had  not 
extended  to  these  countries.  Priestley,  Caven- 
dish, and  Scheele  could  not  be  induced  to  accept 
the  new  doctrine.  It  was,  however,  accepted  by 


La  Revolution  Chimique        113 

Black,  and  its  principles  taught  by  him  in  Edin- 
burgh; and  before  the  end  of  the  century  it  had 
practically  supplanted  phlogistonism  in  this 
country.  Some  of  those  who,  like  Kirwan,  had 
energetically  opposed  the  new  theory  ended  by 
enthusiastically  embracing  it.  Its  introduction 
into  Germany  was  mainly  due  to  the  influence  of 
Klaproth. 

We  further  owe  to  Lavoisier  the  recognition 
of  the  principle  which  lies  at  the  basis  of  chemical 
science  —  the  principle  of  the  conservation  of 
matter.  Lavoisier  was  not  the  first  to  introduce 
the  use  of  the  balance  into  chemistry:  quanti- 
tative chemistry  did  not  actually  originate  with 
him.  Boyle,  Black,  and  Cavendish,  as  a  matter 
of  fact,  preceded  him  in  recognising  the  import- 
ance of  studying  the  quantitative  relations  of 
substances.  Nevertheless,  no  one  before  him 
so  clearly  foreshadowed  the  doctrine  of  the 
indestructibility  of  matter,  and  it  was  mainly 
through  his  teaching  that  the  balance  came  to 
be  recognised  as  indispensable  to  the  pursuit  of 
chemistry.  Before  his  untimely  death  he  had 
succeeded  in  impressing  upon  the  science  the 
main  features  which  at  present  characterise  it. 

Lavoisier  was  one  of  the  most  distinguished 
men  of  his  age,  and  his  merits  as  a  philosopher 
were  recognised  throughout  Europe.  Indeed, 
it  is  not  too  much  to  say  that  at  the  time  of  his 
death  he  was  the  dominant  figure  in  the  chemical 


ii4  History  of  Chemistry 

world  of  the  eighteenth  century.  In  addition  to 
his  position  as  a  member  of  the  Ferine-general 
he  was  made  by  Turgot  a  commissioner  of  the 
Regie  des  Poudres;  and  in  this  capacity  he 
effected  improvements  in  the  manufacture  and 
refining  of  saltpetre,  and  greatly  increased  the 
ballistic  properties  of  gunpowder.  He  became 
Secretary  of  the  Committee  of  Agriculture,  and 
drew  up  reports  on  the  cultivation  of  flax,  of  the 
potato,  and  on  the  liming  of  wheat;  he  prepared 
a  scheme  for  the  establishment  of  experimental 
farms,  and  for  the  collection  and  distribution 
of  agricultural  implements.  He  introduced 
the  cultivation  of  the  beet  root  in  the  Blesois, 
and  improved  the  breed  of  sheep  by  the  im- 
portation of  rams  and  ewes  from  Spain.  He 
was  successively  member  of  the  Assembly  of 
the  Orleanais,  Depute  suppleant  of  the  States- 
General,  and  of  the  Commune  of  Paris.  In  1791 
he  was  named  Secretary  and  Treasurer  of  the 
famous  Commission  of  Weights  and  Measures, 
out  of  which  grew  the  international  system, 
based  theoretically  on  a  natural  unit,  known  as 
the  metric  system,  and  now  adopted  by  most 
civilised  countries  in  the  world.  He  was  not 
only  the  administrative  officer  of  the  Commis- 
sion: he  contributed  to  the  nomenclature  of  the 
system,  and  directed  the  determination  of  the 
physical  constants  on  which  the  measurements 
rested,  and  especially  the  determination  of  the 


LAVOISIER  AND  BERTHOLLET 

in  the  Laboratory  of  the  Sorbonne,  Paris. 


n6  History  of  Chemistry 

weight  of  the  unit  volume  of  water  on  which  the 
value  of  the  standard  of  mass  was  based.  Lastly 
he  was  Treasurer  of  the  French  Academy  until 
its  suppression  in  1793  by  the  Convention, 
which  shortly  afterwards  ordered  the  arrest  of 
Lavoisier  and  others  of  the  Fermiers-generaux 

-  twenty-eight  in  all.  They  were  sentenced 
to  be  executed  within  twenty-four  hours,  and 
their*  property  confiscated.  Coffinhal,  who  pro- 
nounced their  doom,  declared :  "  La  republique  n'a 
pas  besoin  de  savants."  Thus  in  the  fifty-first 
year  of  his  age,  perished  the  creator  of  modern 
chemistry  —  a  victim  to  the  senseless,  sanguin- 
ary fury  of  the  "Friends  of  the  People."  His 
rectitude,  his  public  services,  the  purity  of  his 
private  life,  the  splendour  of  his  scientific 
achievements  —  all  were  unheeded.  As  La- 
grange  said  to  Delambre:  "It  required  but  a 
moment  to  strike  off  this  head ;  a  hundred  years 
may  not  suffice  to  reproduce  such  another. ' ' 

Of  the  men  who  were  associated  with  Lavoisier 
in  the  creation  of  what  was  known  at  the  period 
as  the  antiphlogistic  chemistry,  the  most  emi- 
nent was  Berthollet. 

Claude-Louis  Berthollet  was  born  in  Savoy 
in  1748,  and,  after  a  medical  education,  became 
physician  to  the  Duke  of  Orleans.  Devoting 
himself  to  chemistry,  in  1781  he  was  made  a 
member  of  the  Academy,  and  he  became  Govern- 
ment Commissary  and  Director  of  the  Gobelins, 


La  Revolution  Chimique        117 

the  chief  tinctorial  establishment  of  France. 
Although  in  the  main  in  agreement  with 
Lavoisier,  he  never  wholly  subscribed  to  the 
idea  that  all  acids  contained  oxygen.  He  dis- 
covered the  bleaching  power  of  chlorine,  prepared 
potassium  chlorate,  and  investigated  prussic  acid 
and  fulminating  silver. 

In  his  Statiquc  Chimique,  published  in  1803,  he 
combated  the  partial  and  imperfect  views  of 
Bergman  and  GeofTroy  with  regard  to  the  opera- 
tion of  chemical  affinity,  and  showed  that  the 
direction  of  a  chemical  change  is  modified  by 
the  relative  proportion  of  the  reacting  substances 
and  the  physical  conditions  —  temperature,  pres- 
sure, etc.  —  under  which  the  change  is  effected. 
He  was  one  of  the  first  to  draw  attention 
to  a  class  of  phenomena  known  as  reversible 
reactions,  and  gave  a  number  of  instances 
of  their  occurrence.  Berthollet  pushed  his. 
conclusions  so  far  that  he  was  led  to  doubt 
that  chemical  combination  took  place  in  fixed 
and  definite  proportions ;  and  his  views  gave  rise 
to  a  memorable  controversy  between  him  and 
Proust,  in  which  the  latter  eventually  triumphed. 

Berthollet  enjoyed  a  great  reputation  in  his 
time,  and  played  a  considerable  part  in  the 
political  history  of  his  country.  It  wras  largely 
to  his  zeal,  sagacity,  and  skill  in  developing  her 
internal  resources  at  a  critical  period  when 
she  was  hemmed  round  by  foreign  troops  and 


n8  History  of  Chemistry 

her  ports  blockaded  by  British  ships,  that 
France  was  saved  from  conquest.  His  life  was 
more  than  once  in  jeopardy  when  France  was 
governed  by  a  Committee  of  Public  Safety; 
but  his  honesty,  sincerity,  and  courage  even 
impressed  Robespierre,  and  .  he  escaped  the 
perils  of  the  Great  Terror.  He  was  an  intimate 
friend  of  Napoleon,  and  accompanied  him  to 
Egypt  as  a  member  of  the  Institute.  He  died 
at  Arcueil  in  1822. 

Davy,  who  visited  him  at  his  country  house  in 
1813,  says  of  him:  — 

Berthollet  was  a  most  amiable  man;  when 
the  friend  of  Napoleon,  even,  always  good, 
conciliatory,  and  modest,  frank  and  candid. 
He  had  no  airs,  and  many  graces.  In  every 
way  below  La  Place  in  intellectual  powers,  he 
appeared  superior  to  him  in  moral  qualities. 
Berthollet  had  no  appearance  of  a  man  of 
genius;  but  one  could  not  look  on  La  Place's 
physiognomy  without  being  convinced  that  he 
was  a  very  extraordinary  man. 

Other  notable  men  of  this  period  were  Four- 
croy,  Vauquelin,  Klaproth,  and  Proust. 

Antoine-Francois  Fourcroy,  the  son  of  a 
pharmacist,  was  born  at  Paris  in  1755,  and 
started  his  career  as  a  dramatic  author.  On  the 
advice  of  Vicq  d'Azir,  the  anatomist,  he  turned 
to  medicine,  and  in  1784,  by  the  influence  of 
Buff  on,  obtained  the  chair  of  Chemistry  at  the 
Jardin  du  Roi,  in  succession  to  Macquer.  He 


La  Revolution  Chimique        119 

was  an  excellent  teacher  —  clear,  orderly,  and 
methodical.  He  had,  indeed,  a  talent  for  ora- 
tory. This  he  assiduously  cultivated,  and  be- 
came one  of  the  most  popular  lecturers  of  his 
time  in  France.  Ambitious  and  time-serving, 
he  became  embroiled  in  the  turbulent  politics 
of  the  period,  and,  after  a  chequered  career, 
died,  embittered  and  disappointed,  in  the  fifty- 
fourth  year  of  his  age.  His  chief  services  to 
science  consisted  in  his  works >  Systeme  des 
Connaissances  Chimiques  and  Philosophic  Chi- 
mique. These,  no  less  than  his  public  lectures,  did 
much  to  popularise  the  doctrines  of  Lavoisier 
among  his  countrymen. 

Louis  Nicolas  Vauquelin,  the  son  of  a  Norman 
peasant,  was  born  in  1763,  and  while  a  boy 
became  assistant  to  an  apothecary  in  Rouen. 
In  1780  he  came  to  Paris,  and  entered  Fourcroy's 
laboratory.  Much  of  the  experimental  work 
published  in  Fourcroy's  name  was  actually  done 
by  Vaucfuelin.  He  became  a  member  of  the 
Academy  in  1791,  Professor  of  Chemistry  at 
the  Mining  School,  Assayer  to  the  Mint,  and 
subsequently  Professor  of  Chemistry  at  the 
Jardin  des  Plantes.  On  Fourcroy's  death  he  was 
made  Professor  of  Chemistry  of  the  Medical 
Faculty  of  Paris.  Vauquelin  was  no  theorist; 
he  was,  however,  an  excellent  practical  chemist, 
and  one  of  the  best  analysts  of  the  period.  He 
made  a  large  number  of  mineral  analyses,  more 


120  History  of  Chemistry 

particularly  for  Hauy,  the  crystallographer.  He 
discovered  the  element  chromium  in  the  so- 
called  red-lead  ore  (lead  chromate)  from  Siberia. 
He  also  first  made  known  the  existence  of 
glucinum  in  beryl.  He  described  a  method  of 
separating  the  platinum  metals,  and  worked 
upon  iridium  and  osmium.  He  investigated  the 
hyposulphites,  cyanates,  and  malates.  He  dis- 
covered the  presence  of  benzole  acid  in  the 
urine  of  animals;  with  Robiqet,  he  first  isolated 
asparagin;  with  Buniva,  allantoic  acid;  and  with 
Bouillon  de  la  Grange,  camphoric  acid. 

Vauquelin  lived  wholly  for  science,  and  had 
no  other  interests  than  in  his  laboratory.  He 
was  pensioned  in  1822,  and  died  at  his  birth- 
place —  St.  Andre  d'Heberlot  —  in  the  sixty- 
sixth  year  of  his  age. 

Martin  Heinrich  Klaproth,  born  in  1743  at 
Wernigerode,  in  .the  Hartz,  began  life,  like  Vau- 
quelin, as  an  apothecary's  apprentice  at  Quedlin- 
burg.  Thence  he  went  to  Hanover,  and  ultimately 
to  Berlin,  where  he  studied  under  Pott  and  Marg- 
graf  and  entered  the  pharmacy  of  Valentine 
Rose,  father  of  Heinrich  Rose,  the  distinguished 
chemist,  and  Gustav  Rose,  the  mineralogist.  In 
1788  he  became  a  member  of  the  Berlin  Academy, 
and,  on  the  creation  of  the  Berlin  University  in 
1809,  was  made  Professor  of  Chemistry.  As 
already  stated,  he  was  the  first  chemist  of  em- 
inence in  Germany  to  adopt  the  antiphlogistic 


La  Revolution  Chimique        121 

theory.  He  was  distinguished  as  an  analyst. 
He  discovered  tellurium,  analysed  pitchblende 
and  uranit,  and  first  made  known  the  existence 
of  uranium,  zirconium,  and  cerium,  which  he 
termed  "ocliroita. "  He  analysed  corundum, 
and  was  an  independent  discoverer  of  titanium 
and  glucinum,  termed  by  him  beryllium.  He 
made  a  large  number  of  analyses  of  minerals, 
such  as  leucite,  chrysoberyl,  hyacinth,  granite, 
olivin,  wolfram,  malachite,  pyromorphite,  etc. 
He  continued  actively  at  work  until  his  death, 
in  the  seventy-fourth  year  of  his  age. 

Analytical  chemistry  is  under  great  obligations 
to  Klaproth.  He  established  a  standard  of 
accuracy  never  before  approached;  and  much 
of  h'is  analytical  work,  both  as  regards  processes 
and  results,  is  of  permanent  value. 

Joseph  Louis  Proust,  the  son  of  a  pharmacist 
was  born  at  Angers  in  1761.  He  received  his 
early  training  in  chemistry  from  his  father,  and, 
after  studying  under  Rouelle  in  Paris,  obtained 
an  appointment  at  the  Salpetriere.  Proust  has 
the  credit  of  being  the  first  chemist  to  make  a 
balloon  ascent  —  in  a  Montgolfier  balloon  with 
Pilatre  de  Rozier.  On  the  invitation  of  the  King 
of  Spain,  he  went  to  that  country  to  superintend 
certain  chemical  manufacturing  processes.  He 
became  Professor  of  Chemistry  at  the  University 
of  Salamanca,  and  subsequently  went  to  Madrid, 
where  he  was  installed  in  a  well-equipped  labora- 


122  History  of  Chemistry 

tory  to  enable  him  to  examine  the  mineral  riches 
of  Spain.  On  the  breaking  out  of  war  his  work 
was  interrupted,  and  he  was  obliged  to  leave  Ma- 
drid. His  laboratory  was  completely  destroyed, 
and  his  valuable  collection  of  apparatus  and 
specimens  dissipated.  Through  the  good  offices 
of  Berthollet,  Proust  was  offered  a  consider- 
able sum  of  money  by  Napoleon  in  order  to 
induce  him  to  turn  his  discovery  of  grape  sugar 
to  practical  account.  Proust  was,  however, 
too  broken  in  health  to  undertake  the  work  of 
a  factory  manager,  and  he  retired  to  Mayence. 
On  the  restoration  of  the  Monarchy  he  was 
made  a  member  of  the  French  Academy,  his 
honorarium  as  an  Academician  being  augmented 
by  a  pension  from  Louis  XVIII.  He  died  in 
1826,  while  on  a  visit  to  Angers,  his  native  place. 
Proust  is  the  discoverer  of  what  is  now  styled 
"the  law  of  constant  proportion,"  which  states 
that  the  same  body  is  invariably  composed  of 
the  same  elements,  united  in  the  same  proportion. 
He  was  a  skilful  analyst,  and  made  numerous 
analyses  of  minerals;  and  he  was  one  of  the 
earliest  to  undertake  a  systematic  study  of 
metallic  salts  of  organic  acids. 


CHAPTER   IX 
THE  ATOMIC  THEORY 

T^HE  opening  years  of  the  nineteenth  century 
were  made  memorable  by  the  promulgation 
of  the  atomic  theory  by  John  Dalton.  The 
enunciation  of  this  theory,  which  affords  a  simple 
and  adequate  explanation  of  the  fundamental 
laws  of  chemical  combination,  marks  an  epoch 
in  the  history  of  chemistry. 

It  may  be  desirable  to  trace,  as  briefly  as 
possible,  the  successive  steps  which  led  up  to  the 
generalisation  which  more  than  any  other  has 
served  to  stamp  chemistry  as  an  exact  science. 
That  matter  was  discrete  —  that  is,  that,  it  was 
not  continuous,  but  was  composed  of  ultimate 
particles  —  was,  as  already  stated,  imagined  by 
the  ancients,  and  was  part  of  the  philosophy  of 
Leukippus,  Demokritus,  and  Leucretius.  But 
this  supposition,  although  favoured  by  Newton 
and^  other  thinkers,  had  little  or  no  scientific 
basis  prior  to  the  middle  of  the  eighteenth  cen- 
tury. From  that  time  onward  a  variety  of 
chemical  facts  gradually  accumulated,  many  of 
which  at  the  time  of  their  discovery  had  no 
obvious  connection  with  pre-existing  facts.  It 
was  reserved  for  Dalton  to  point  out  how  an 

123 


124  History  of  Chemistry 

extension  and  more  precise  definition  of  the 
old  doctrine  would  suffice  to  connect  and  explain 
them. 

The  first  germ  of  an  atomic  theory  based  on 
chemical  fact  may  he  traced  in  the  observation 
of  Toburn  Bergmann  (b.  1735,  d.  1784), 
Professor  of  Chemistry  at  Upsala,  that  neutral 
solutions  of  certain  metals  in  contact  with  other 
metals  gave  a  precipitate  without  the  neutrality 
of  the  solution  being  disturbed,  and  without  gas 
being  evolved.  One  metal  had  simply  replaced 
the  other  in  solution.  Bergmann  thus  inciden- 
tally discovered  the  fact  of  the  chemical  equiva- 
lence of  metals.  He  was  of  opinion,  however, 
that  the  phenomenon  meant  a  transference  of 
phlogiston  from  one  metal  to  another,  and  that 
the  process  might  be  made  a  mode  of  deter- 
mining the  relative  amount  of  phlogiston  in 
various  metals.  Lavoisier  extended  Bergmann's 
observations,  and  sought  to  show,  in  effect,  that 
the  process  afforded  a  means  of  determining  the 
amounts  of  the  several  metals  which  combined 
with  one  and  the  same  quantity  of  oxygen.  But 
neither  Bergmann  nor  Lavoisier  really  grasped 
the  idea  of  equivalence  as  we  understand  it 
to-day.  It  began  to  be  appreciated  as  the  result 
of  the  work  of  Jeremiah  Benjamin  Richter 
(b.  1762,  d.  1807)  and  of  G.  E.  Fischer  on  the 
mutual  action  of  salts  in  solutions,  and  on  the 
determinations  of  the  amounts  of  acid  and 


The  Atomic  Theory  125 

bases  which  respectively  combine  with  one 
another.  Methods  of  measurement  of  the 
proportions  in  which  substances  combine  were 
grouped  by  Richter  under  the  term  Stochiometry. 

However  desirable  it  may  be  in  the  interests 
of  history  to  indicate  the  sequence  of  the  sur- 
mises and  facts  which  preceded  the  formulation 
of  the  atomic  theory,  it  is  very  doubtful  whether 
Dalton  was,  to  any  material  extent,  influenced 
by  them.  A  self-educated  man  of  lowly  origin, 
sturdily  independent  and  highly  original,  he  was 
accustomed  to  rely  upon  his  own  faculty  of 
observation  and  experiment  for  his  facts,  and 
upon  his  own  intellectual  powers  and  mental 
energy  for  their  interpretation. 

John  Dalton,  the  son  of  a  Quaker  hand-loom 
weaver,  was  born  at  Eaglesfield,  in  Cumberland, 
in  1766.  While  still  a  boy  he  took  to  school- 
teaching,  and  acquired,  in  his  leisure  and  by 
his  own  exertions,  a  competent  knowledge  of 
mathematics  and  physical  science.  In  1793  he 
was  called  to  give  instruction  in  mathematics, 
natural  philosophy,  and  chemistry  at  the 
Manchester  New  College,  the  Nonconformist 
academy  —  now  moved  from  Warrington  — 
in  which  Priestley  had  formerly  lectured.  Here 
he  remained  six  years,  leaving  the  college  to 
take  up  an  independent  position  as  a  private 
tutor,  so  as  to  enable  him  the  more  freely  to 
pursue  his  scientific  inquiries.  In  1800  he  be- 


126  History  of  Chemistry 

came  Secretary  of  the  Philosophical  Society  of 
Manchester,  and  remained  connected,  as  an 
official,  with  that  institution  until  his  death  in 
1844.  The  greater  number  of  his  scientific 
communications  were  published  by  that  society. 
In  the  outset  of  his  scientific  career  he  was 
attracted  to  meteorology;  and  it  was  probably 
its  problems  which  led  him  in  the  first  place  to 
experiment,  and  to  speculate  on  the  physical 
constitution  of  gases.  In  the  course  of  these 
observations  he  was  led  to  the  discovery  of  the 
law  of  thermal  expansion  of  gases,  with  which  his 
name  is  now  generally  associated.  His  specula- 
tions concerning  the  physical  constitution  of 
gaseous  substances,  arising  from  the  contempla- 
tion of  gaseous  phenomena,  led  him  to  the  con- 
ception that  a  gas  is  composed  of  particles  that 
repel  one  another  with  a  force  decreasing  as  the 
distance  of  their  centres  from  each  other;  and 
it  is  probable  that  in  this  manner  he  familiarised 
himself  with  the  idea  of  the  existence  of  atoms. 
His  first  insight  into  the  laws  of  the  chemical 
combination  of  these  atoms  seems  to  have 
originated  from  his  discovery  that,  when  two 
substances  unite  in  different  proportions,  these 
proportions  may  be  expressed  in  simple  multi- 
ples of  whole  numbers.  Thus  he  found,  on 
examining  the  composition  of  marsh  gas  and  of 
ethyl'ene,  both  hydrocarbons,  that  for  the  same 
weight  of  hydrogen  there  was  twice  the  amount  • 


JOHN  DALTON. 

From  a  painting  by  B.  R.  Faulkner  in  the  possession  of  the  Royal  Society 


127 


128  History  of  Chemistry 

of  carbon  in  ethylene  that  there  was  in  marsh 
gas.  He  then  examined  the  oxides  of  nitrogen, 
and  found  a  similar  regularity  to  hold  good 
in  these  compounds.  Some  time  prior  to  the 
autumn  of  1803  Dalton  was  led  to  the  supposition 
that  these  regularities  could  be  satisfactorily 
explained  by  the  assumption  that  matter  is 
composed  of  atoms  having  sizes  and  weights 
differing  with  each  substance,  but  of  identical 
weight  and  size  for  any  particular  substance, 
and  that  chemical  combination  consists  in  the 
approximation  of  these  atoms.  This  simple 
hypothesis  explained  all  the  facts  then  known. 
It  explained  the  constancy  in  the  chemical 
composition  of  substances,  which  may  be  said  to 
have  been  established  by  Proust,  and  which  is 
now  formulated  as  the  Law  of  Constant  Propor- 
tion —  that  the  same  body  is  invariably  com- 
posed of  the  same  elements,  united  in  the  same 
proportion.  It  explained  also  the  fact  dis- 
covered by  Dalton  that,  when  an  element  unites 
with  another  in  different  proportions,  the  higher 
proportions  are  multiples  of  the  lowest  —  now 
formulated  as  the  Law  of  Multiple  Proportion. 
It  further  explained  the  fact,  which  may  be 
said  to  have  been  foreshadowed  by  Richter, 
that  when  two  bodies,  A  and  B,  separately 
combine  with  a  third  body,  C,  the  proportions 
of  A  and  B  which  unite  with  C  are  measures  or 
multiples  of  the  proportions  in  which  A  and  B 


The  Atomic  Theory  129 

combine  together.  This  is  known  as  the  Law  of 
Reciprocal  Proportion. 

Dalton's  theory  was  first  made  generally 
known  by  Thomas  Thomson,  in  the  third  edition 
of  his  System  of  Chemistry,  published  in  1807, 
and  was  employed  by  Thomson  in  his  paper  on 
"The  Oxalates  of  Strontium,"  published  the 
same  year  in  the  Philosophical  Transactions. 
The  first  printed  account  by  Dalton  himself  is 
contained  in  Part  I.  of  his  New  System  of 
Chemical  Philosophy,  published  in  1808,  the 
substance  of  which  had  been  previously  given 
in  a  course  of  lectures  at  the  Royal  Institution, 
London,  and  subsequently  repeated  in  Edin- 
burgh and  Glasgow. 

The  statement  of  his  theory  is  contained  in 
chapter  iii.  of  this  work,  under  the  heading  "Of 
Chemical  Synthesis,"  and  is  accompanied  by 
a  plate  and  explanation,  of  which  a  facsimile  is 
given  on  pp.  130-1. 

The  facts  upon  which  Dalton  based  his  theory 
are  incontrovertible;  but  Dalton's  explanation 
of  them  was  not  universally  accepted  at  the 
time  he  gave  it.  Davy,  who,  of  course,  was 
familiar  with  the  conception  of  atoms  as  part 
of  the  Newtonian  philosophy,  objected  to  the 
term  "atomic  weight"  introduced  by  Dalton, 
and  suggested  the  expression  "  combining  pro- 
portion"; and  Wollaston,  for  similar  reasons, 
proposed  the  term  "equivalent,"  as  denoting 


ELEMENTS 


o  0 


93456  6 

ft    £>    151 


O     © 


it          u  14  15          16 


17  18  19 


J&tttnty 

21  22  23 

OO      00     (DO 


25 

O® 


Ternary 

060  000  oio  oio 


54 


37 


130 


The    illustration    on    the    preceding    page    contains 
the   arbitrary  marks  or  signs  chosen  to  represent   the 
several  chemical  elements  or  ultimate  particles. 
Fig.  Fig. 


1.  Hydro,  its  rel.  weight  i 

2.  Azote 5 

3.  Carbone  or  charcoal.    5 

4.  Oxygen .    7 

5.  Phosphorus 9 

6.  Sulphur   13 

7.  Magnesia 20 

8.  Lime 23 

9.  Soda 28 

10.   Potash 42 


1 1.  Strontites 46 

12.  Barytes 68 

13.  Iron 38 

14.  Zinc 56 

15.  Copper 56 

16.  Lead 95 

17.  Silver 100 

18.  Platina 100 

19.  Gold 140 

20.  Mercury 167 


21.  An  atom  of  water  or  steam,  composed  of  i  of 

oxygen  and  i  of  hydrogen,  retained  in  physi- 
cal contact  by  a  strong  affinity,  and  sup- 
posed to  be  surrounded  by  a  common  atmos- 
phere of  heat ;  its  relative  weight  = 8 

22.  An  atom  of  ammonia,  composed  of  i  of  azote 

and  T  of  hydrogen 6 

23.  An  atom  of  nitrous  gas,  composed  of  i  of  azote 

and  i  of  oxgyen 12 

24.  An  atom  of  olefiant  gas,  composed  of  i  of  car- 

bone  and  i  of  hydrogen 6 

25.  An  atom  of  carbonic  oxide  composed  of  i  of 

carbone  and  i  of  oxygen 12 

26.  An  atom  of  nitrous  oxide,  2  azote  +  i  oxygen  .      17 

27.  An  atom  of  nitric  acid,  i  azote  +  2  oxygen  ....     19 

28.  An    atom    of    carbonic    acid,    i    carbone  +  2 

oxygen 19 

29.  An  atom  of  carburetted  hydrogen,   i  carbone 

+  2  hydrogen 7 

30.  An  atom  of  oxynitric  acid,  i  azote  +3  oxygen  .     26 

3 1 .  An  atom  of  sulphuric  acid,  i  sulpuur  +  3  oxygen     34 

32.  An  atom  of  sulphuretted  hydrogen,  i  sulphur 

+  3  hydrogen 16 

33.  An  atom  of  alcohol,  3  carbone  +  i  hydrogen ...      16 

34.  An  atom   of   nitrous    acid,    i    nitric    acid  +  i 

nitrous  gas 31 

35.  An  atom  of  acetous  acid,  2  carbone  +  2  water  .      26 

36.  An  atom  of  nitrate  of  ammonia,  i  nitric  acid 

+  i  ammonia  +  i  water 33 

37.  An  atom  of  sugar,  i  alcohol  +  i  carbonic  acid     35 

•si 


132,  History  of  Chemistry 

the  constant  quantity  with  which  bodies  went 
in  and  out  of  combination.  There  is  no  doubt 
that  the  use  of  these  terms  retarded  the  general 
acceptance  of  Dalton's  doctrine,  and,  moreover, 
brought  into  the  science  a  confusion  which  was 
not  finally  dispelled,  as  we  shall  see,  until  during 
the  second  half  of  the  century. 

Dalton's  estimations  of  the  relative  weights  of 
the  atoms,  or,  to  use  Davy's  phrase,  the  values 
of  their  combining  proportions,  were,  as  might 
be  expected,  very  rough  approximations  to  the 
truth.  This  arose  partly  from  inadequate  ex- 
perimental data,  and  partly  from  uncertainty 
as  to  the  relative  number  of  the  constituent 
atoms  which  made  up  a  compound.  Neither 
Dalton  nor  his  immediate  successors  had  any 
rational  or  consistent  method  of  determining 
the  latter  point.  The  view  taken  of  the  com- 
position of  the  compound  decided  what  parti- 
cular multiples  or  sub-multiples  of  the  values 
of  the  atomic  weights  of  its  constituents  were  to 
be  adopted.  As  Dalton,  in  many  cases,  had  no 
real  criterion  to  guide  him,  he  made  the  simplest 
possible  assumptions;  but  these  might  or  might 
not  be  valid;  and  subsequent  experience  showed 
that  in  some  cases  they  were  erroneous. 

It  was,  however,  generally  recognised  that 
these  atomic  weights,  combining  proportions,  or 
equivalents,  as  they  were  for  a  time  indifferently 
termed,  were  chemical  constants  of  the  highest 


The  Atomic  Theory  133 

importance,  both  to  the  scientific  chemist,  who, 
apart  from  their  theoretic  interest,  had  need  of 
them  in  the  course  of  quantitative  analysis,  and 
to  the  manufacturing  chemist,  who  required 
them  for  the  intelligent  exercise  of  his  operations; 
and  accordingly  a  number  of  chemists,  very 
shortly  after  the  promulgation  of  Dalton's  theory, 
attempted  to  determine  their  values  with  all 
possible  precision.  Chief  among  these  was  the 
Swedish  chemist  Berzelius,  to  whom  science  was 
indebted  for  a  series  of  estimations  of  atomic 
weights,  which  were  long  regarded  as  models  of 
quantitative  accuracy,  and  stamped  their  Author 
as  the  greatest  master  of  determinative  chem- 
istry of  his  age. 

Jons  Jakob  Berzelius,  the  son  of  a  school- 
master, was  born  near  Linkoping,  in  East  Goth- 
land, Sweden,  in  1779.  Entering  Upsala  with 
a  view  to  the  profession  of  medicine,  he  was 
attracted,  under  the  influence  of  Afzelius  —  or, 
rather,  in  spite  of  it  —  to  the  study  of  chemistry, 
and,  later,  of  voltaic  electricity,  then  in  its  in- 
fancy. While  holding  a  number  of  minor  ap- 
pointments as  a  teacher  of  medicine,  pharmacy, 
physics,  and  chemistry,  he  was  elected,  in  1808, 
a  member  of  the  Swedish  Academy  of  Sciences, 
of  which  he  became  President  iniSio.  Ini8i8 
he  was  made  permanent  Secretary  of  the  Acad- 
emy, and,  by  means  of  a  yearly  subsidy,  was 
enabled  to  devote  himself  wholly  to  experimental 


134  History  of  Chemistry 

science.  He  was  ennobled  in  1818,  and  on  the 
occasion  of  his  marriage,  in  1835,  was  created  a 
baron  of  the  Scandinavian  kingdom.  He  died 
in  1848. 

Berzelius  occupies  a  pre-eminent  position  in 
the  history  of  chemistry,  and  during  a  consider- 
able portion  of  his  lifetime  exercjsed  an  almost 
unassailable  authority  as  a  chemical  philosopher. 
He  is  distinguished  as  an  experimenter,  as  a 
discoverer,  as  a  critic  and  interpreter,  and  as  a 
lawgiver.  His  contributions  to  chemical  know- 
ledge range  over  every  department  of  the  science. 
He  shares  with  Davy  the  honour  of  having  es- 
tablished the  fundamental  laws  of  electrochem- 
istry. His  experimental  work  on  the  atomic 
weights  of  the  elements  —  the  great  work  of  his 
life  —  was  of  supreme  importance  at  this  partic- 
ular period  of  the  development  of  chemistry: 
it  served  not  only  to  give  precision  to,  and 
enhance  the  significance  and  value  of,  Dalton's 
generalisation,  but  it  furnished  chemists,  for  the 
first  time,  with  a  set  of  constants,  ascertained 
with  the  highest  exactitude  of  which  opera- 
tive chemistry  was  then  capable,  thereby  con- 
tributing to  the  expansion  of  quantitative 
analysis,  and  to  a  more  exact  knowledge  of  the 
composition  of  substances.  Berzelius,  indeed, 
was  an  analyst  of  the  first  rank  —  conscientious, 
patient,  and  painstaking;  an  ingenious  and  skil- 
ful manipulator;  inventive  and  resourceful. 


The  Atomic  Theory  135 

What  determinative  chemistry  owes  to  his  la- 
bours, and  not  less  to  his  example,  is  obvious 
from  even  the  most  superficial  examination  of  its 
literature  during  the  first  third  of  the  last  century. 

As  a  discoverer,  Berzelius  first  made  known  the 
existence  of  cerium  (1803),  of  selenium  (1818), 
and  of  thorium  (1828);  and  he  prepared  and  in- 
vestigated a  large  number  of  their  combinations. 
He  isolated  silicon  (1823),  zirconium  (1824), 
tantalum  (1824),  and  studied  the  compounds 
of  vanadium,  discovered  by  his  countryman 
Sefstrom.  He  largely  extended  our  knowledge 
of  groups  of  substances  in  which  sulphur  replaces 
oxygen;  investigated  compounds  of  fluorine 
(1824),  platinum  (1828),  and  tellurium  (1831— 
1833),  and  made  many  analyses  of  minerals, 
meteorites,  and  mineral- waters.  He  discovered 
racemic  acid  and  investigated  the  ferrocyanides. 
It  was  his  investigation  of  racemic  acid  — 
which  has  the  same  percentage  composition  as 
tartaric  acid  —  that  first  enabled  him  to  grasp 
the  conception  of  isomerism,  a  term  which  we 
owe  to  him,  and  of  metamerism  and  polymer  ism. 
He  was  the  first  to  study  the  phenomena  of 
contact-actions,  which  he  comprehended  under 
the  term  catalysis. 

As  an  author  his  literary  activity  was  aston- 
ishing. His  new  system  of  mineralogy  marks 
an  epoch  in  the  history  of  that  branch  of  science. 
His  text-book  on  chemistry  was  long  the  leading 


JONS  JAKOB  BERZELIUS. 

From  a  painting  by  J.  G.  Sandberg. 


136 


The  Atomic  Theory  137 

manual,  and  went  through  many  editions,  being 
constantly  revised  by  him.  His  annual  reports 
on  the  progress  of  physics  and  chemistry  ex- 
tended to  twenty-seven  volumes  and  constitute 
a  monument  to  his  industry,  thoroughness, 
perspicacity,  and  critical  ability. 

Although  holding  no  university  appointment, 
and  with  a  laboratory  of  the  most  modest 
dimensions  and  character,  Berzelius,  exercised 
great  influence  as  a  teacher.  Some  of  the  most 
notable  chemists  of  the  last  century,  such  as 
Heinrich  and  Gustav  Rose,  Dulong,  Mitscherlich, 
Wohler,  Chr.  Gmelin,  and  Mosander,  were  among 
his  pupils;  and  many  of  them  have  testified  to 
his  stimulating  power  as  an  investigator  of 
'nature,  and  to  his  merits  as  a  worthy,  genial 
man. 

The  reasonableness  of  Dalton's  conjecture 
received  further  support  from  the  discovery  by 
Gay  Lussac  in  1808,  that  gases  always  combine 
in  simple  proportions  by  volume,  and  that  the 
volume  of  the  gaseous  product  formed,  when 
measured  under  comparable  conditions  of  tem- 
perature and  pressure,  stands  in  a  simple 
relation  to  the  volumes  of  the  constituents.  The 
law  of  pressure  discovered  by  Boyle,  that  of 
thermal  expansion  by  Dalton,  and  of  volumes 
by  Gay  Lussac  (which,  it  ought  to  be  stated, 
was  previously  and  independently  made  by 
Dalton),  are  explained  on  the  assumption  that 


138  History  of  Chemistry 

equal  numbers  of  the  particles  —  either  as 
simple  particles  or  as  compound  particles  - 
are  present  in  the  same  volume  of  the  gas. 
This  method  of  explanation  was  first  clearly 
stated  by  the  Italian  physicist  Avogadro  in 
1811,  but  its  significance,  as  will  be  seen 
subsequently,  was  not  appreciated  until  half 
a  century  later. 

As  the  values  for  the  .atomic  weights  gradually 
became  more  exact,  speculations  arose  as  to  the 
significance  of  the  numerical  relations  which  were 
observed  to  exist  among  them.  In  1815 
William  Prout  threw  out  the  supposition  that 
the  atomic  weights  of  the  gaseous  elements  are 
multiples  by  whole  numbers  of  that  of  hydrogen. 
Extended  into  a  generalisation,  this  might  be 
held  to  indicate  that  all  kinds  of  matter  are  so 
many  forms  of  a  primordial  substance.  Subse- 
quent inquiry  showed  that  Prout 's  "Law, "  as 
it  is  sometimes  called,  was  not  tenable  in  its 
original  form.  Certain  elements,  it  was  conclu- 
sively proved,  had  atomic  weights  which  were 
not  whole  numbers.  Dumas  subsequently  modi- 
fied the  law,  after  a  redetermination  of  a  large 
number  of  atomic  weights,  by  assuming  that 
the  substance  common  to  the  so-called  elements 
had  a  lower  atomic  weight  than  unity.  Al- 
though there  are  a  considerable  number  of 
elements  whose  atomic  weights,  based  upon  the 
most  accurate  determinations,  are  remarkably 


The  Atomic  Theory  139 

close  to  whole  numbers,  the  investigations  of 
Stas  and  others  afford  no  valid  reason  for  be- 
lieving that  Prout's  hypothesis,  and  the  under- 
lying supposition  to  which  it  has  been  held  to 
point,  are  justified  by  experimental  evidence. 


CHAPTER   X 
THE  BEGINNINGS  OF  ELECTRO-CHEMISTRY 

PHE  first  year  of  the  nineteenth  century  is 
further  memorable  on  account  of  the  inven- 
tion of  the  voltaic  pile,  and  by  reason  of  its 
application  by  William  Nicholson  and  Sir 
Anthony  Carlisle  to  the  electrolytic  decom- 
position of  water.  This  mode  of  resolving  water 
into  its  constituents  made  a  great  sensation  at 
the  time,  mainly  because  of  the  extraordinary 
method  by  which  it  was  effected.  It  afforded 
an  independent  and  unlooked-for  proof  of  the 
compound  nature  of  water  by  a  method  alto- 
gether differing  in  principle  from  that  by  which 
its  composition  had  been  previously  ascertained. 
The  formation  of  water  by  the  combustion  of 
hydrogen  brought  no  conviction  of  its  real 
nature  to  a  confirmed  phlogistian  like  Priestley; 
and  it  is  even  doubtful  whether  Cavendish  ever 
fully  realised  the  true  significance  of  his  great 
discovery.  But  the  fact  that  the  quantitative 
results  of  the  analysis  thus  effected  were  identical 
with  those  of  its  synthesis,  as  made  by  Caven- 
dish and  Lavoisier,  admitted  of  only  one  inter- 
pretation. This  cardinal  discovery  may  be  said 
to  have  completed* the  downfall  of  phlogiston. 
140 


Electro-Chemistry  141 

The  value  of  the  voltaic  pile  as  an  analytical 
agent  was  nowhere  more  quickly  appreciated 
than  in  England.  In  the  hands  of  Humphry 
Davy  its  application  to  the  analysis  of  the 
alkalis  and  alkaline  earths  led  to  discoveries  of 
the  greatest  magnitude. 

Humphry  Davy  was  born  in  Penzance  in  1778. 
In  the  course  of  his  studies  for  the  profession  of 
medicine  he  was  attracted  to  chemistry;  and  he 
became  chemical  assistant  to  Dr.  Beddoes,  a 
former  teacher  of  chemistry  at  Oxford,  but  then 
living  at  Clifton,  near  Bristol.  While  in  the 
capacity  of  assistant  and  operator  in  Beddoes's 
Pneumatical  Institute,  Davy  discovered  the 
intoxicating  properties  of  nitrous  oxide  (so  called 
laughing  gas),  which  brought  him  into  promi- 
nence and  led  to  his  engagement  by  the  managers 
of  the  newly-created  Royal  Institution  in  London 
as  lecturer  in  chemistry  in  succession  to  Garnett. 
He  early  began  to  experiment  on  galvanism, 
and  soon  succeeded  in  developing  the  fundamen- 
tal laws  of  electro-chemistry;  and  in  1807  he 
effected  the  decomposition  of  potash  and  soda  by 
the  application  of  voltaic  electricity  —  thereby 
establishing,  what  indeed  had  been  surmised 
previously,  that  the  alkalis  are  compound  sub- 
stances. He  subsequently  proved  that  this  was 
also  the  case  with  the  alkaline  earths.  Davy 
thus  added  some  five  or  six  metallic  elements 
to  those  already  known. 


142  History  of  Chemistry 

These  discoveries,  perhaps  the  most  brilliant 
of  their  time,  afforded  additional  evidence  of  the 
invalidity  ot  Lavoisier's  assumption  that  oxygen, 
as  the  name  implies,  was  the  "principle  of 
acidity,"  The  surmise,  in  fact,  was  already 
disproved  by  the  case  of  water  —  a  neutral 
substance  and  devoid  of  all  the  recognised 
attributes  of  an  acid.  It  was  still  further  dis- 
proved by  the  cases  of  potash  and  soda  — 
strongly  alkaline  compounds. 

Additional  evidence  was  adduced  by  Davy 
in  demonstrating,  in  1810,  that  the  so-called 
oxymuriatic  acid,  the  de  phlogistic  ate  d  marine 
acid  discovered  by  Scheele,  contained  no  oxygen, 
but  was  a  simple,  indivisible  substance.  For 
the  old  designation,  which  connoted  a  compound 
body,  he  substituted  the  name  chlorine,  in 
allusion  to  the  characteristic  colour  of  the 
element.  In  the  course  of  his  investigation  on 
this  substance  he  discovered  the  "  penta-  and 
trichloride  of  phosphorus,  chlorophosphamide  and 
chlorine  peroxide.  He  was  also  the  discoverer  of 
telluretted  hydrogen  and  an  independent  dis- 
coverer of  nitrosulphonic  acid, 

He  worked  on  iodine  and  the  iodates,  on  the 
diamond,  on  the  so-called  fuming  liquor  of  Cadet, 
on  nitrogen  chloride,  and  on  the  pigments  of  the 
ancients.  Lastly,  he  invented  the  miner's 
safety  lamp,  with  which  his  name  will  always  be 
associated,  effecting  thereby  what  was  praq- 


SIR  HUMPHRY  DAVY. 

From  a  painting  by  Lawrence  in  the  possession  of  the  Royal  Society. 


144  History  of  Chemistry 

tically  a  revolution  in  coal-mining.  He  became 
President  of  the  Royal  Society  in  1820,  and  died 
at  Geneva  on  May  29th,  1829,  in  the  fifty-first 
year  of  his  age.  Davy  was  a  singularly  gifted 
man,  of  great  mental  vigour  and  imaginative 
power;  quick,  lively  and  ingenious;  an  eloquent 
teacher  and  a  daring  and  brilliant  experimenter. 
Another  noteworthy  name  in  the  chemical 
history  of  this  period  is  Wollaston.  William 
Hyde  Wollaston,  born  at  East  Dereham,  in 
Norfolk,  in  1766,  was  .educated  at  Cambridge 
with  a  view  to  the  profession  of  medicine,  but, 
failing  to  secure  a  practice,  he  devoted  himself 
to  the  pursuit  of  science,  and  especially  to  op- 
tics and  chemistry.  He  devised  a  method  of 
working  platinum,  and  was  the  first  to  make 
known  the  existence  of  palladium  and  rhodium. 
He  was  one  of  the  most  ingenious  and  acute 
analysts  of  his  time,  and  possessed  remarkable 
inventive  powers.  He  investigated  the  nature 
of  urinary  calculi  and  chalk  stones.  His  paper  on 
the  oxalates  of  potash  was  of  great  service  at  the 
time  as  a  demonstration  of  the  law  of  multiple 
proportions.  He  first  drew  attention  to  the 
existence  in  the  solar  spectrum  of  what  were 
subsequently  termed  the  Fraunhofer  lines;  and 
he  invented  the  reflecting  goniometer  and  the 
camera  lucida,  and  a  slide  rule  for  chemical 
calculations.  He  resembled  Cavendish  in  tem- 
perament and  mental  habitudes,  and,  like  him, 


WILLIAM  HYDE  WOLLASTON. 

From  a  painting  by  J.  Jackson,  R.A.,  in  the  possession  of  the 
Royal  Society. 


146  History  of  Chemistry 

was  distinguished  for  the  range  and  exactitude 
of  his  scientific  knowledge,  his  habitual  caution, 
and  his  cold  and  reserved  disposition.  He  died 
in  1828. 

Almost  immediately  after  the  publication  of 
Volta's  discovery  attempts  were  made  —  notably 
by  Berzelius  in  Sweden  and  by  Davy  in  England 
-  to  prove  that  electrical  and  chemical  pheno- 
mena are  correlated  and  mutually  dependent. 
This  assumption  was  more  fully  worked  out  by 
Berzelius  in  1812,  and  it  served  as  the  basis  of 
a  chemical  system  which  exercised  considerable 
influence  on  chemical  doctrine  during  the  first 
half  of  the  nineteenth  century. 

Berzelius  assumed  that  electric  polarity  was  an 
attribute  of  all  atoms  —  that  these  were  bipolar, 
in  fact,  but  that  in  them  either  positive  or  nega- 
tive electricity  predominated.  Hence  the  ele- 
ments were  capable  of  being  divided  into  two 
classes  —  that  is,  positive  or  negative,  depending 
upon  the  excess  of  either  charge.  Which  of  the 
electricities  predominated  might  be  ascertained 
by  determining  the  particular  pole  at  which  the' 
element  was  separated  on  electrolysis.  Com- 
binations of  dissimilar  elements  —  or,  in  other 
words,  chemical  compounds  —  were  also  en- 
dowed with  polarity.  The  chemical  affinities  of 
elements  and  compounds  were  related  to  the  ex- 
cess of  either  kind  of  electricity  resident  in  them; 
and  chemical  combination  resulted  from,  and  was 


Electro-Chemistry  147 

a  consequence  of,  the  more  or  less  perfect  neu- 
tralisation of  the  two  kinds.  From  a  study  of 
the  electrical  deportment  of  the  elements  Berze- 
lius  sought  to  arrange  them  in  series,  starting 
with  oxygen  as  the  most  electro-negative  member. 

These  conceptions  were  employed  by  him  as 
the  basis  of  a  method  of  classification.  The  at- 
tempt is  historically  interesting  as  being  the  first 
systematic  endeavour  to  gain  an  insight  into  the 
constitution  of  chemical  compounds  —  that  is,to 
determine  the  manner  in  which  the  constituent 
atoms  are  grouped  or  arranged  with  respect  to 
one  another,  or,  in  other  words,  to  distinguish 
between  the  empirical  and. the  rational  composi- 
tion of  substances,  which  is  the  ultimate  aim  of 
modern  chemistry. 

A  necessary  consequence  of  these  views  was 
that  every  compound  was  to  be  considered  as 
made  up  of  two  parts  in  electrically  different 
states.  Thus  baryta,  consisted  of  a  combination 
of  the  electro-positive  barium,  combined  with 
the  electro-negative  oxygen;  it  combined  with 
sulphuric  oxide  because  the  preponderating 
positive  electricity  it  contained  met  with  the 
negative  electricity  which  prevailed  in  the  sul- 
phuric oxide.  Generalising,  it  may  be  said  that 
the  basic  oxides  are  invariably  the  positive  con- 
stituents of  salts,  whereas  the  acid  oxides  are 
the  negative  constituents,  as  proved  by  the 
mode  in  which  the  two  kinds  of  oxides  sep- 


148  History  of  Chemistry 

arated  at  the  poles  on  electrolysis.  Barium 
sulphate,  then,  was  to  be  regarded  as  made  up 
of  two  entities  —  BaO  and  SO3  —  and  hence 
was  to  be  called  sulphate  of  baryta.  Berzelius 
extended  this  conception  in  order  to  explain 
the  formation  of  double  salts  —  such,  for  ex- 
ample, as  potash  alum,  which  he  regarded 
as  a  binary  compound  of  positive  potassium 
sulphate  and  negative  aluminium  sulphate,  each 
of  which,  in  its  turn,  could  be  resolved  into  an 
acidic  and  a  basic  oxide  of  opposite  electricities. 
The  dualistic  notions  of  Berzelius  led  him  to 
the  construction  of  a  system  of  chemical  nomen- 
clature and  notation  which,  in  its  main  fea- 
tures, has  persisted  to  this  day,  and  is  universally 
current,  with  certain  modifications,  in  modern 
chemical  literature.  We  owe  to  him  the  group- 
ing of  the  elements  into  metals  and  metalloids, 
and  also  our  present  system  of  symbolic  notation, 
whereby  even  complicated  chemical  reactions 
may  be  expressed  in  a  concise  and  intelligible 
manner.  Chemical  symbols  were  used  by  the 
alchemists;  but  Berzelius  first  suggested  that  a 
chemical  symbol  should  not  only  represent  the 
element  to  which  it  refers,  but  also  its  relative 
atomic  weight.  Chemical  equations  became 
quantitative  as  well  as  qualitative  expressions 
of  the  facts  they  denote.  Such  equations  im- 
plicitly assumed  that,  to  use  Davy's  words, 
chemistry  had  passed  under  the  dominion  of  the 


Electro-Chemistry  149 

mathematical  sciences.  Professed  mathemati- 
cians were,  however,  slow  to  recognise  that  the 
phenomena  of  chemical  action  were  capable  of 
formal  mathematical  treatment.  Davy  relates 
that  on  speaking  to  Laplace  of  the  atomic  theory 
in  chemistry,  and  expressing  his  belief  that  the 
science  would  ultimately  be  referred  to  mathe- 
matical laws  similar  to  those  he  had  so  pro- 
foundly and  successfully  established  with  respect 
to  the  mechanical  properties  of  matter,  the  idea 
was  treated  in  a  tone  bordering  on  contempt. 

Berzelius's  electro-chemical  system,  and  the 
dualistic  ideas  associated  with  it,  were  of  con- 
siderable service  when  applied  to  the  inorganic 
branch  of  the  science;  but  attempts  to  fit  them  to 
the  facts  of  organic  chemistry,  which  began  to 
accumulate  rapidly  after  the  first  quarter  of  the 
century,  failed.  Its  inadequacy  as  a  compre- 
hensive generalisation  became  more  and  more 
manifest,  and  it  eventually  fell.  In  fact,  it  may 
be  said  to  have  received  its  death-blow  by  Davy's 
discovery  of  the  elementary  nature  of  chlorine, 
and  by  the  recognition  of  the  fact  that  the  acids 
do  not  necessarily  contain  oxygen.  Davy  and, 
later,  Dulong  made  it  obvious  that,  if  any  one 
element  was  to  be  regarded  as  the  acidifying 
principle,  it  was  hydrogen,  and  not  oxygen;  and, 
in  a  sense,  this  view  ultimately  prevailed  in  the 
recognition  of  the  acids  as  salts  of  hydrogen. 

In  France  the  study  of  electro-chemistry  was 


History  of  Chemistry 

undertaken  by  Gay  Lussac  and  Thenard,  largely 
owing  to  the  action  of  the  Emperor  Napoleon, 
who  furnished  the  funds  for  the  construction  of 
a  powerful  galvanic  battery.  The  results  were 
published,  in  1811,  under  the  title,  Recherches 
Physico-Chimiques,  faites  sur  la  Pile,  etc.  Gay 
Lussac,  whose  name  has  already  been  men- 
tioned as  one  of  the  discoverers  of  the  Law 
of  Combination  of  Gases,  played  a  considerable 
part  in  the  history  of  chemistry  at  this  period. 
He  was  one  of  the  earliest  to  appreciate  the  im- 
portance of  Dalton's  generalisation,  and  to  point 
out  the  significance  of  his  own  discovery  in 
strengthening  it.  He  was  probably  led,  in  the  first 
instance,  to  the  recognition  of  the  law  of  gaseous 
combination  by  Berthollet's  work  on  the  volumet- 
ric composition  of  ammonia  gas,  and  by  his  own 
discovery — made  in  1805,  in  conjunction  with 
Humboldt,  in  the  course  of  their  analysis  of 
atmospheric  air  —  that  one  volume  of  oxygen 
combined  with  exactly  two  volumes  of  hydrogen 
to  form  water.  The  regularities  thus  indicated 
he  found  to  be  general :  all  gases  which  are  capable 
of  chemical  union  combine  in  simple  proportions 
by  volume,  and  the  volume  of  the  product,  if  a 
gas,  always  stands  in  some  simple  relation  to  the 
volumes  of  the  constituents. 

Joseph  Louis  Gay  Lussac  was  born  in  1778, 
at  Saint  Leonard,  studied  chemistry  in  Paris, 
and  was  associated  in  chemical  inquiry  with 


Electro-Chemistry  151 

Berthollet.  As  Eleve-Ingenieur  in  the*  Ecole 
Nationale  des  Fonts  et  des  Chaussees  he  began 
the  experimental  work  in  physics  and  chemistry 
upon  which  his  fame  rests.  In  1804  he  under- 
took, with  Biot,  a  series  of  balloon  ascents  for 
the  purpose  xof  investigating  the  physics  and 
chemistry  of  the  upper  regions  of  the  atmosphere. 
In  1806  he  became  Professor  of  Chemistry  at 
the  Ecole  Polytechnique,  and  in  1832  Professor 
at  the  Jardin  des  Plantes.  He  was  one  of  the 
chief  assayers  of  the  French  Mint,  and,  as  member 
of  many  commissions,  exerted  considerable  in- 
fluence in  official  circles.  He  died  in  1850. 

Gay  Lussac  and  Thenard  were  the  first  to 
devise  a  method  of  obtaining  potassium  and 
sodium  by  a  purely  chemical  process,  whereby 
these  metals  could  be  procured  in  far  larger  quan- 
tities than  was  at  that  time  possible  by  electro- 
lytic means.  They  were  thus  enabled  to  make 
use  of  the  strong  deoxidising  power  of  these 
metals  to  effect  a  number  of  reductions,  notably 
that  of  boric  oxide  to  boron.  Gay  Lussac  and 
Thenard  were  also  the  first  to  make  known  the 
existence  of  boron  fluoride.  We  further  owe  to 
Gay  Lussac  the  discovery  of  cyanogen,  the  first 
of  the  so-called  compound  radicals.  He  first 
prepared  ethyl  iodide,  investigated  sulphovinic 
acid  and  grape  sugar,  studied  etherification  and 
fermentation,  etc.  We  are  also  indebted  to  him 
for  a  method  of  determining  vapour  densities 


152  History  of  Chemistry 

which 'proved  of  great  service  in  ascertaining  the 
molecular  weights  of  substances.  He  worked 
on  iodine  and  its  compounds,  discovered,  with 
Welter,  thiosulphuric  acid,  and  investigated 
fulminic  acid  in  collaboration  with  Liebig. 

Among  his  services  to  analytical  chemistry 
were  his  method  for  the  analysis  of  gunpowder, 
his  volumetric  estimation  of  silver  (wet  silver 
assay),  chlorometric  analysis,  alkalimetry,  etc. 
He  devised  the  system  still  in  use  in  France  for 
the  estimation  of  alcohol  in  spirits  of  wine. 

Louis  Jacques  Thenard  was  born  in  1777  at 
Nogent-Sur-Seine,  and  was  a  pupil  of  Vauquelin 
and  of  Berthollet.  In  1797  he  became  repetiteur 
at  the  Polytechnic  School  of  Paris,  and  eventu- 
ally its  professor.  He  subsequently  occupied 
the  chair  of  chemistry  at  the  College  de  France, 
and  of  the  Faculty  of  Science  of  the  University 
of  Paris.  He  was  ennobled  by  Charles  X.  in 
1824,  and  died  at  Paris  in  the  eightieth  year  of 
his  age. 

In  addition  to  his  work  with  Gay  Lussac 
already  mentioned,  we  owe  to  Thenard  the 
discovery  of  hydrogen  peroxide  and  hydrogen 
persulphide.  Together  with  Dulong  he  studied 
the  catalytic  action  of  platinum  on  mixtures  of 
oxygen  and  hydrogen.  He  investigated  the 
fatty  acids,  and  worked  on  fermentation  and  on 
ether- formation ;  and  he  was  the  first  to  isolate 
citric  and  malic  acids.  He  also  occupied  him- 


Electro-Chemistry  153 

self  .with  the  chemistry  of  bile,  perspiration, 
albumen,  the  acids  of  urine  and  milk,  and  with 
the  theory  of  mordants. 

In  1834  Faraday  made  known  the  important 
fact  that  on  passing  the  same  galvanic  current 
through  a  number  of  electrolytes  —  water, 
hydrochloric  acid,  solutions  of  metallic  chloride 
—  these  were  decomposed  in  such  manner  that 
definite  amounts  of  hydrogen  or  metal  were 
separated  at  the  negative  pole,  and  correspond- 
ing amounts  of  oxygen  or  chlorine  were  evolved 
at  the  positive  pole.  These  observations  were 
comprehended  by  Faraday  under  his  "law 
of  definite  electrolytic  action."  The  electro- 
chemical equivalents  thus  obtained  were  in  some 
cases  identical  with  the  atomic  weights  deduced 
by  Berzelius;  in  others  they  were  not;  but, 
nevertheless,  when  they  differed,  they  stood  in 
some  simple  relation  to  the  assumed  atomic 
weight.  The  significance  of  Faraday's  observa- 
tion was  not  lost  sight  of,  although  his  anticipa- 
tion that  the  determination  of  electro-chemical 
equivalents  would  be  of  use  in  fixing  atomic 
weights  was  not  immediately  appreciated.  A 
clear  distinction  between  the  equivalent,  the  atom, 
and  the  molecule  was  not  then  apprehended. 
As  will  be  subsequently  shown,  it  was  only 
during  the  latter  half  of  the  nineteenth  century 
that  the  discrepancies  and  inconsistencies  thus 
revealed  were  definitely  reconciled  and  cleared  up. 


CHAPTER   XI 
THE  FOUNDATIONS  OF  ORGANIC  CHEMISTRY 

A  S  the  horizon  of  chemistry  widened  and  its 
**  operations  extended,  it  became  necessary 
to  treat  its  subject-matter  methodically.  Ac- 
cordingly attempts  were  made  in  the  various 
systematic  treatises  which  began  to  appear  in 
the  seventeenth  century  to  group  its  facts  into 
an  orderly  and  rational  arrangement.  One  of 
the  earliest  of  such  systematic  treatises  was  the 
Cours  de  Chimie  of  Nicolas  Lemery,  published 
in  1675.  Although  this  work  was  styled  by 
Boerhaave  "a  tumultuary  mass  of  pharma- 
ceutical processes,  without  any  certain  design 
or  coherence,"  it  is  noteworthy  as  being  the 
first  of  its  kind  to  divide  the  science  into  its 
present  main  branches  of  inorganic  and  organic 
chemistry. 

It  may  be  desirable  to  indicate,  as  briefly  as 
possible,  the  general  state  of  knowledge  respect- 
ing the  chemistry  of  organic  substances  down  to 
the  early  years  of  the  last  century.  As  already 
mentioned,  such  substances  as  acetic  acid, 
turpentine,  starch,  sugar,  certain  dye  stuffs,  and 
oils,  had  long  been  known;  and  such  processes 
as  saponification  and  fermentation  had  been 

154 


Organic  Chemistry  155 

practised  from  very  early  times.  The  alchem- 
ists had  prepared  a  variety  of  essential  oils, 
aliphatic  ethers,  and  esters;  and  the  iatro- 
chemists  had  obtained  benzoic  and  succinic  acids, 
and  acetic  acid  from  wood.  Milk  sugar  was 
first  prepared  by  Fabrizio  Bartoletti  in  1619. 
Grape  sugar  was  first  mentioned  as  occurring 
in  honey  by  Glauber  in  1660.  Boyle  first 
detected  the  presence  of  a  spirit  among  the 
products  of  the  destructive  distillation  of  wood. 
Few  of  the  followers  of  Stahl  occupied  them- 
selves with  organic  products;  and  it  was  only 
towards  the  end  of  the  phlogistic  period  that 
attention  was  once  more  directed  to  products  of 
animal  and  vegetable  origin.  Scheele  isolated 
glycerin  in  1784,  and  obtained  ethyl  chloride  by 
the  distillation  of  a  mixture  of  common  salt, 
pyrolusite,  oil  of  vitriol,  and  alcohol.  Ethyl 
acetate  was  first  prepared  by  Lauraquais  in  1759. 
Arvidson  obtained  ethyl. formate  in  1777.  Oxalic 
ether  was  first  made  by  Savary  in  1773.  What 
was  long  known  as  oil  of  wine  appears  to  have 
been  first  mentioned  by  Libavius,  but  its  true 
nature  was  discovered  by  Hennel  in  1826.  The 
formation  of  aldehyde  was  first  recognised  by 
Scheele  in  1774,  and  it  was  in  turn  investigated 
by  Fourcroy  and  Vauquelin,  Dobereiner,  and 
Gay  Lussac;  but  it  was  first  definitely  isolated 
in  1835  by  Liebig,  who  gave  it  its  name. 

The    first    organic   acid    known   was    vinegar 


156  History  of  Chemistry 

(acetic  acid),  and  for  a  long  time  all  naturally 
occurring  organic  acids  having  a  sour  taste  were 
regarded  as  identical  with  or  as  forms  of  vinegar. 
It  was  only  during  the  second  half  of  the  eigh- 
teenth century  that  it  was  clearly  ascertained 
that  a  variety  of  organic  acids  exist,  perfectly 
distinct  from  acetic  acid.  Glacial  acetic  acid 
was  first  obtained  by  Lowiz  in  1789.  Acetic 
acid,  as  a  product  of  the  destructive  distillation 
of  wood,  was  first  obtained  by  Gottling  in  1779. 
The  acetic  fermentation  has  been  studied  from 
very  early  times.  Surmises  as  to  the  mode  in 
which  wine  was  converted  into  vinegar  are  to 
be  met  with  in  the  works  of  Basil  Valentine, 
Becher  (1669),  Lemery  (1675),  and  Stahl  (1667). 
Priestley,  for  a  time,  held  the  opinion  that 
vinegar  contained  a  vegetable  acid  air,  but  he 
subsequently  discovered  and  corrected  his  error. 
The  direct  conversion  of  spirit  o.f  wine  (ethyl 
alcohol)  into  acetic  acid  was  studied  by  Lavoisier 
and  Berthollet,  who  first  clearly  recognised  that 
it  was  a  process  of  oxidation.  The  quantitative 
composition  of  acetic  acid  was  first  established 
by  Berzelius  in  1814.  Many  of  the  acetates  have 
been  known  from  early  times.  Verdigris  is  men- 
tioned by  Theophrastus,  Dioscorides,  and  Pliny. 
Zinc  acetate  was  known  to  Geber,  and  potassium 
acetate  to  Pliny,  who  mentions  its  use  in  medicine. 
Ammonium  acetate  was  also  used  in  medicine  as 
far  back  as  the  beginning  of  the  seventeenth 


Organic  Chemistry  157 

century,  and  was  particularly  recommended  by 
the  physician,  Raymond  Minderer.  Sodium 
acetate  was  prepared  by  Duhamel  in  1736. 
Lead  acetate  was  known  in  the  fifteenth  century, 
and  was  styled  by  Libavius  saccharum  plumbi 
quintessential,  in  allusion  to  its  sweet  taste. 
What  was  called  by  the  alchemists  lac  virginis 
was  a  turbid  solution  of  basic  lead  acetate,  and 
it  was  frequently  used  in  medicine,  more  parti- 
cularly by  Goulard  in  1760.  What  we  now  call 
acetone  was  first  observed  by  Libavius,  in  1595, 
and  subsequently  by  Boyle,  during  the  destruc- 
tive distillation  of  lead  acetate:  its  formation 
from  other  acetates  was  noticed  by  TrommsdorfT, 
Derosne,  and  Chenevix,  by  whom  it  was  termed 
pyroacetic  spirit.  Its  true  nature  and  composi- 
tion were  first  ascertained  by  Liebig  in  1831. 

The  formation  of  tartar  in  the  manufacture  of 
wine  has  been  known  from  the  earliest  times. 
It  was  regarded  as,  and  originally  styled,  the 
faex  vini.  The  word  " Tartarus"  is  first  met 
with  in  alchemistic  literature  in  the  eleventh 
century,  and  is  the  Latinised  form  of  an  Arabic 
word.  Marggraf,  in  1764,  recognised  that  the 
tartar  of  wine  contained  potash;  but  tartaric 
acid  itself  was  first  isolated  by  Scheele  in  1769. 

The  double  tar tr ate  of  potash  and  soda  was  first 
prepared  in  1672  by  Peter  Seignette,  an  apothe- 
cary of  Rochelle,  and  was  used  by  him  in  medi- 
cine. Tartar  emetic  was  discovered  by  Adrian 


158  History  of  Chemistry 

von  Mynsicht  in  1631,  and  its  true  nature 
explained  by  Bergmann  in  1773.  Racemic  acid 
was  first  mentioned  by  a  wine  manufacturer 
named  Kestner,  and  was  recognised  as  an  acid 
in  1819.  Its  relation  to  tartaric  acid,  with 
which  it  is  isomeric,  was  first  explained  by 
Berzelius,  who  gave  it  its  name. 

The  naturally  occurring  oxalates  were  long 
considered  as  identical  with  tartar.  Oxalic  acid 
was  obtained  by  Scheele  in  1776  by  means  of  the 
action  of  nitric  acid  upon  sugar.  This  acid  was 
further  investigated  by  Bergmann,  who  observed 
its  decomposition  by  heat  with  the  formation 
of  a  gas  burning  with  a  blue  flame.  The 
identity  of  the  naturally  occurring  oxalic  acid 
with  that  prepared  from  sugar  was  established 
by  Scheele  in  1784.  The  quantitative  composi- 
tion of  oxalic  acid  was  first  ascertained  by 
Dulong  in  1815.  Mucic  acid  was  discovered 
by  Scheele  in  1780,  and  was  studied  by  Fourcroy, 
who  gave  it  the  name  it  now  bears.  Pyromucic 
acid  was  also  known  to  Scheele,  and  was  observed 
by  Hermbstadt  and  Houton-Labillardiere.  Cam- 
phoric  acid  was  first  recognised  by  Bouillon- 
Lagrange  and  Vauquelin.  Suberic  acid  was 
discovered  by  Brugnatelli  in  1787. 

That  gum  benzoin  yielded  a  product  (benzole 
acid)  by  sublimation  was  known  in  the  sixteenth 
century.  It  was  introduced  into  medicine  by 
Turquet  de  Mayerne  as  flowers  of  benzoin. 


Organic  Chemistry  159 

Scheele  showed  how  this  acid  might  be  obtained 
by  wet  methods  from  gum-benzoin.  It  was 
detected  in  Peru-balsam  by  Lehmann  in  1709. 
Rouelle  found  it  in  the  urine  of  the  cow  and  the 
camel.  Liebig,  in  1829,  detected  the  difference 
between  hippuric  acid  and  benzoic  acid.  The 
characteristic  acid  in  amber  (succinic  acid)  was 
first  detected  by  Pott  in  1753. 

Formic  acid  was  first  isolated  by  Wray  in  1676. 
Lactic  acid  was  discovered  by  Scheele  in  sour 
milk  in  1780.  For  a  time  it  was  regarded  as 
impure  acetic  acid,  until  it  was  detected  in  muscle 
juice  by  Berzelius,  and  its  individuality  estab- 
lished. Its  true  composition  was  ascertained  by 
Mitscherlich  and  by  Liebig  in  1832.  Citric  acid 
has  been  known  since  the  thirteenth  century, 
but  it  was  first  definitely  isolated  by  Scheele 
in  1784.  Apple  juice  was  used  in  medicine  in 
the  sixteenth  century,  and  the  soda  salt  of  its 
characteristic  acid  (malic  acid)  was  prepared  by 
Donald  Monro  in  1767. 

It  was  known  to  the  ancients  that  extract  of 
gall  nuts  acquired  a  black  colour  when  mixed 
with  a  solution  of  iron  vitriol;  and  Boyle  and 
Bergmann  ascribed  this  phenomenon  to  the 
presence  of  a  peculiar  acid.  Gallic  acid  was 
first  isolated  by  Scheele  in  1785,  and  its  com- 
position established  by  Berzelius  in  1814. 
Tannic  acid  was  definitely  recognised  as  distinct 
from  gallic  acid  by  Seguin  in  1795. 


160  History  of  Chemistry 

Mellite,  or  honey-stone,  is  mentioned  in  min- 
eralogical  treatises  in  the  sixteenth  century. 
That  it  consisted  of  the  alumina  salt  of  a  special 
acid  (mellic  acid)  was  shown  by  Klaproth  in  1799. 

Prussian  blue  was  accidentally  discovered  in 
1710  by  a  dyer  named  Diesbach.  Its  mode  of 
manufacture  was  first  made  known  by  Wood- 
ward in  1724.  The  peculiar  reaction  by  which 
it  was  obtained  was  made  the  subject  of  investi- 
gation by  many  chemists  of  the  period  without 
any  decisive  result.  Scheele  observed  that, 
when  the  salt  which  occasioned  the  blue  colour 
with  vitriol  was  distilled  with  sulphuric  acid,  a 
volatile  acid,  inflammable  and  soluble  in  water, 
was  obtained.  This  acid  received  from  Berg- 
mann  the  name  of  acidum  ccerulei  berolinensis, 
or  "Berlin-blue  acid,"  subsequently  shortened 
by  Guyton  de  Morveau  to  prussic  acid.  Scheele 
also  prepared  the  cyanides  of  silver  and  am- 
monium. That  prussic  acid  was  free  from  oxy- 
gen was  established  by  Berthollet.  Anhydrous 
prussic  acid  was  first  obtained  by  Von  Ittner, 
who  first  established  its  highly  poisonous  nature. 
Bolim,  in  1802,  had  previously  observed  the 
presence  of  prussic  acid  in  oil  of  bitter  almonds, 
the  poisonous  character  of  which  was  known  to 
Dioscorides.  Porret.  first  definitely  isolated  potas- 
sium ferrocyanide ,  and  subsequently  discovered 
the  thiocyanates ,  the  quantitative  composition 
of  which  was  ascertained  by  Berzelius  in  1820. 


Organic  Chemistry  161 

That  prussic  acid  was  a  compound  of  hydrogen 
and  cyanogen  was  established  by  Gay  Lussac  in 
1815. 

Cyanic  acid  was  discovered  by  Wohler  in 
1822,  in  which  year  also  L.  Gmelin  discovered 
the  ferricyanides. 

Fulminating  mercury  was  first  prepared  by 
Howard  in  1800,  and  fulminating  silver  by  Brug- 
natelli  in  1 802 .  These  were  recognised  by  Liebig, 
in  1822,  to  contain  a  peculiar  acid,  which  he 
termed  fulminic  acid,  and  which  he  showed  to 
have  the  same  composition  as  the  cyanic  acid 
discovered  by  Wohler.  Uric  acid,  so  named  by 
Fourcroy,  was  discovered  in  gall  stones  by  Scheele 
in  1776.  Urea  was  first  definitely  isolated  by 
Fourcroy  and  Vauquelin  in  1799,  and  was  syn- 
thetically prepared  by  Wohler  in  1828. 

The  bitter  principles  of  plants  and  their  me- 
dicinal virtues  early  attracted  attention,  but  the 
first  attempt  to  isolate  them  was  made  by  Four- 
croy and  Vauquelin  in  the  case  of  the  Peruvian 
bark,  long  known  for  its  power  as  a  febrifuge. 
In  1806  Vauquelin  obtained  quinic  acid.  Cin- 
chonine  was  first  isolated  by  Gomes  in  1811. 

The  chemical  nature  of  opium  was  the  subject 
of  numerous  inquiries  in  the  early  years  of  the 
nineteenth  century.  In  1805  Serturner  detected 
the  existence  of  meconic  acid,  and  in  1817  that 
of  morphine,  which  he  recognised  as  an  alkaloid. 
Narcotine  was  discovered  by  Robiquet  in  1835. 


162  History  of  Chemistry 

The  investigation  of  other  bitter  substances  was 
undertaken  by  Pelletier  and  Caventou,  who  in 
1818  discovered  strychnine,  brucine  (1819),  and 
veratrine  (1820). 

The  contemporaries  and  immediate  followers 
of  Lavoisier  were  the  first  to  make  a  systematic 
attempt  to  elucidate  the  chemical  nature  of  or- 
ganic products  of  animal  origin.  To  this  period 
belongs  the  work  of  Fourcroy  and  Vauquelin  on 
animal  chemistry.  Chevreul,  a  pupil  of  Fourcroy 
worked  on  urine,  adipocire,  and  the  animal  fats 
in  the  first  decade  of  the  last  century.  Kirchhoff 
in  1811,  discovered  the  method  of  converting 
starch  into  sugar;  and  Dobereiner,  in  1822,  de- 
scribed a  method  of  preparing  formic  acid  arti- 
ficially. Dumas  and  Boullay,  in  1827-1828, 
prepared  a  number  of  new  derivatives  of  ethyl 
alcohol;  and  in  1834  Dumas  and  Peligot  studied 
in  like  manner  the  chemistry  of  methyl  alcohol, 
and  pointed  out  many  analogies  which  their  com- 
pounds possessed,  not  only  among  themselves, 
but  also  to  inorganic  substances. 

Although  a  considerable  amount  of  informa- 
tion as  to  the  existence,  modes  of  occurrence,  and 
properties  of  bodies  found  in  the  animal  and 
vegetable  kingdoms  had  been  accumulated  by 
the  end  of  the  first  quarter  of  the  nineteenth  cen- 
tury, no  serious  attempt  was  made  to  study  them 
systematically  until  after  that  period.  In  fact, 
they  were  not  even  regarded  as  coming  within 


Organic  Chemistry  163 

the  operations  of  laws  found  to  be  applicable  to 
the  products  of  the  inorganic  world,  by  the  in- 
vestigation, of  which  products,  indeed,  those  laws 
had  been  discovered. 

Down  to  1828  it  was  considered  that  inorganic 
and  organic  substances  were  sharply  differenti- 
atedby  the  circumstance  that,  whereas  the  former 
might  be  prepared  by  artificial  means,  and  even 
built  up  from  their  elements  by  synthetic  pro- 
cesses in  the  laboratory,  the  latter  could  only  be 
formed  in  the  bodies  of  animals  and  plants  as  the 
result  of  vital  force.  In  that  year  Wohler  showed 
that  urea,  pre-eminently  a  product  of  animal 
metabolism,  could  be  prepared  synthetically 
from  inorganic  materials.  Other  instances  of  a 
similar  kind  were  discovered  in  rapid  succession ; 
and  the  idea  that  organic  substances  could  alone 
be  formed  by  vital  processes  was  proved  to  be 
invalid.  Moreover,  large  numbers  of  substances 
of  a  character  analogous  to  those  produced  by 
physiological  action,  but  not  known  to  occur  in 
the  animal  or  vegetable  kingdom,  were  prepared. 
There  is,  therefore,  no  absolute  distinction  to  be 
drawn  between  the  chemistry  of  the  inorganic 
and  organic  worlds. 

At  the  present  day  we  mean  by  "  organic 
compounds"  simply  the  compounds  of  carbon. 
These  are  so  numerous,  and  frequently  so  com- 
plex, that  it  is  convenient  to  group  them  together 
and  study  them  as  a  special  section  of  the  science. 


164  History  of  Chemistry 

At  the  outset  it  was  supposed  that  only  very 
few  elements  entered  into  the  composition  of 
organic  substances.  This,  indeed,  was  held  to 
be  a  point  of  fundamental  distinction  between 
organic  and  inorganic  compounds.  Lavoisier 
was  of  opinion  that  all  organic  bodies  were  com- 
binations of  carbon,  hydrogen,  and  oxygen. 
Berthollet  first  discovered  the  presence  of  nitro- 
gen in  a  product  of  animal  origin.  Sulphur  and 
phosphorus  were  detected  later.  There  is  appar- 
ently no  a  priori  reason  why  any  element  should 
not  be  associated  with  carbon,  and  enter  into 
the  composition  of  an  organic  compound. 

Lavoisier  was  one  of  the  first  to  devise  methods 
for  ascertaining  the  composition  of  organic 
(carbon)  compounds,  and  to  indicate  the  general 
principles  by  which  the  proportion  of  the  ele- 
ments met  with  in  these  substances  can  be  ascer- 
tained. So  imperfectly,  however,  were  these 
methods  worked  out  that  it  was  not  established 
until  the  close  of  the  first  decade  of  the  nine- 
teenth century  that  organic  compounds  even 
obeyed  the  law  of  multiple  proportions.  Thanks 
to  the  efforts  of  Berzelius,  Gay  Lussac,  and 
Thenard,  and  especially  of  Liebig,  in  1830, 
methods  of  organic  analysis  were  so  far  perfected 
that  it  became  possible  to  ascertain  the  empirical 
composition  of  these  compounds  with  certainty. 
This  point  reached,  the  development  of  this 
section  of  chemistry  proceeded  with  unexampled 


Organic  Chemistry  165 

rapidity.  Not  only  was  the  composition  of 
numbers  of  products,  such  as  sugar,  starch,  the 
vegetable  acids,  certain  alkaloids,  etc.,  estab- 
lished, but  altogether  unlooked-for  facts  became 
manifest.  One  of  the  most  surprising  of  these 
was  that  of  isomerism. 

Up  to  the  close  of  the  first  quarter  of  the 
nineteenth  century  it  seemed  self-evident  that 
substances  of  the  same  percentage  composition 
are  necessarily  identical.  In  1823  Liebig  showed 
that  the  silver  cyanate  of  Wohler  had  the  same 
composition  as  silver  fulminate.  Faraday,  in 
1825,  found  a  hydrocarbon  in  oil  gas,  which  had 
the  same  composition  as  olefiant  gas,  but  was 
otherwise  different  from  it;  and  in  1828  Wohler 
discovered  that  urea  and  ammonium  cyanate  — 
perfectly  dissimilar  substances  —  were  identical 
in  elementary  composition.  Lastly,  Berzelius 
found  this  to  be  true  of  tartaric  and  racemic 
acids;  and  he  thereupon  proposed  the  term 
SDm&rism  to  denote  the  general  fact.  He  fur- 
ther pointed  out  that  the  phenomenon  could 
only  be  explained  by  supposing  that  the  relative 
positions  of  the  atoms  in  isomeric  compounds 
are  different. 

But  the  influence  of  molecular  or  atomic 
grouping  in  determining  the  specific  character  of 
a  substance  is  not  confined  to  compounds.  The 
same  phenomenon  is  observed  to  occur  among 
the  elements.  It  was  conclusively  established 


166  History  of  Chemistry 

by  Lavoisier  that  the  diamond  and  charcoal  are 
chemically  the  same  thing  —  both  forms  of 
carbon.  Scheele  showed  that  graphite  was  a 
third  form  of  carbon.  Phosphorus,  sulphur, 
and  oxygen  were  subsequently  shown  to  be  each 
capable  of  existence  in  various  modifications. 
Instances  of  this  character  were  grouped  together 
in  1841  by  Berzelius  under  the  term  allotropy. 

The  recognition  of  the  fact  of  isomerism 
exerted  a  great  influence  on  the  development  of 
organic  chemistry.  It  ultimately  led  to  the 
assumption  that  particular  groups  of  elements 
or  atomic  complexes,  so-called  radicals,  were  to 
be  found  in  organic  compounds  —  a  conception 
based  originally  on  Gay  Lussac's  discovery  of 
cyanogen,  a  combination  of  carbon  and  nitrogen, 
which  was  found  to  behave  like  a  simple  sub- 
stance, such  as  chlorine,  and  to  give  rise  to 
compounds  analogous  to  the  corresponding 
chlorides.  .This  idea  of  the  existence  of  com- 
pound radicals  was  greatly  strengthened  by  a 
memorable  investigation  by  Liebig  and  Wohler, 
in  i'832,  on  oil  of  bitter  almonds  and  its  deriva- 
tives, in  which  they  showed  that  these  substances 
might  be  represented  as  containing  a  special 
group  or  radical  termed  benzoyl,  which  behaved 
like  an  element.  The  idea  of  groups  of  elements 
going  in  and  out  of  combination  like  a  simple 
substance  was  not  new  to  chemists:  there  was 
not  only  the  case  of  cyanogen,  discovered  by 


Organic  Chemistry  167 

Gay  Lussac  in  1815.  The  attempt  had  been 
made  by  Dumas  and  Boullay  in  1828  to  classify 
the  derivatives  of  alcohol  and  ether  as  com- 
pounds containing  a  common  radical  etherin. 
Gay  Lussac  had  pointed  out  that  the  vapour 
density  of  ethyl  alcohol  seemed  to  show  that 
it  consisted  of  equal  volumes  of  ethylene  and 
water.  Robiquet  had  also  shown  that  ethyl 
chloride  might  be  assumed  to  be  a  compound  of 
hydrochloric  acid  and  ethylene;  and  Dobereiner 
had  regarded  anhydrous  oxalic  acid  as  a  com- 
bination of  carbonic  acid  with  carbonic  oxide. 

But  the  investigation  of  Liebig  and  Wohler 
served  to  give  precision  to  the  conception.  It 
thereby  exercised  a  profound  influence  on  the 
development  of  organic  chemistry  by  demon- 
strating, in  effect,  that  this  branch  of  the  science 
might  be  regarded  as  the  chemistry  of  the  com- 
pound radicals,  in  contradistinction  to  inorganic 
chemistry — the  cherriistry  of  the  simple  radicals. 
Additional  support  for  this  view  was  afforded 
by  the  remarkable  research  by  Bunsen  on  the 
so-called  alkarsin,  the  " fuming  liquor  of  Cadet" 
-  an  evil-smelling  substance  long  known  as 
being  formed  when  an  acetate  is  heated  with  ar- 
senious  oxide.  Bunsen  showed  that  this  liquid 
contained  a  compound  radical  having  arsenic 
as  a  constituent;  and  he  prepared  a  series  of 
derivatives,  all  of  which  might  be  formulated 
as  combinations  of  this  radical,  which  he  termed 


i68  History  of  Chemistry 

cacodyl.  The  study  of  the  electrolytic  decom- 
position of  the  acetates  by  Kolbe  and  the  dis- 
covery of  zinc-ethyl  by  A  Frankland  afforded 
powerful  support  to  the  doctrine  of  combined 
radicals. 

Although  there  can  be  no  doubt  that  this 
doctrine  greatly  stimulated  the  pursuit  of  organic 
chemistry,  it  was  gradually  perceived  that  to 
regard  inorganic  and  organic  chemistry  as  the 
chemistry  respectively  of  the  simple  and  of  the 
compound  radicals  was  an  imperfect  and  mis- 
leading conception  of  the  true  relations  of  the 
two  main  divisions  of  the  science.  Facts 
showed  that  the  properties  of  a  substance  de- 
pend more  on  the  arrangement  of  its  atoms 
than  on  their  nature.  The  doctrine  of  compound 
radicals  was  implicitly  an  attempt  to  extend  the 
dualistic  conceptions  of  Berzelius  to  the  facts  of 
organic  chemistry;  and  as  such  it  was  welcomed 
by  the  great  Swedish  chemist.  But  dualism 
was  found  to  have  its  limitations,  even  in 
inorganic  chemistry;  and  these  were  still  more 
apparent  when  it  was  sought  to  apply  it  in  the 
other  main  branch  of  the  science.  Attempts 
were  therefore  made  -^  notably  by  the  French 
chemists  Laurent,  Dumas,  and  Gerhardt  —  to 
formulate  organic  substances  by  methods  in 
which  the  electro-chemical  and  dualistic  con- 
ceptions of  Berzelius  and  his  followers  had  no 
part.  How  these  attempts  developed,  and  how 


Organic  Chemistry  169 

they  subsequently  grew  into  the  organic  chem- 
istry of  to-day,  will  be  shown  in  the  second  part 
of  this  work. 

It  will  be  convenient  also  to  delay  any 
account  of  the  personal  history  of  the  creators 
of  the  science  of  organic  chemistry  —  Liebig, 
Wohler,  Dumas  —  until  we  are  in  a  position  to 
give  a  fuller  statement  of  their  labours,  and  of 
the  results  which  flowed  from  them.  Although 
the  foundations  of  organic  chemistry  may  be 
said  to  have  been  laid  during  the  closing  years 
of  the  first  half  of  the  nineteenth  century,  the 
superstructure  was  not  erected  until  the  second 
half. 


CHAPTER   XII 
THE  RISE  OF  PHYSICAL  CHEMISTRY 

DHYSICS  and  Chemistry  are  twin  sisters  — • 
*  daughters  of  Natural  Philosophy;  like  Juno's 
swans,  coupled  and  inseparable.  Physics  is 
concerned  with  the  forms  of  energy  which  affect 
'matter;  chemistry  with  the  study  of  matter  so 
affected.  Each,  then,  is  complementary  to  the 
other.  Philosophers  of  old  drew  no  practical  dis- 
tinction between  them,  at  least  as  regards  their 
own  studies.  Men  like  Boyle,  Black,  Cavendish, 
Lavoisier,  Dalton,  Faraday,  Graham,  Bunsen, 
were  pioneers  "  on  a  very  broad  gauge,  "  pushing 
their  inquiries  into  territories  common  to  the  two 
branches  as  their  genius  or  inclinations  directed 
them.  Accordingly,  it  has  happened  that  many 
so-called  physical  laws  have  been  discovered  by 
men  who  were  professed  chemists.  It  has  also 
happened  that  men  who  began  their  scientific 
career  as  chemists,  like  Dalton,  Regnault,  and 
Magnus,  eventually  gave  the  whole  of  their 
energies  to  physical  measurements;  or,  like 
Black,  Faraday,  and  Graham,  devoted  them- 
selves to  the  elucidation  of  physical  problems. 
As  certain  of  these  physical  laws  and  problems 
have  greatly  influenced  the  progress  of  chemis- 
170 


Physical  Chemistry  171 

try,  it  becomes  necessary,  in  any  historical 
treatment  of  the  subject,  to  give  some  account 
of  their  origin,  and  to  show  how  they  affected 
the  development  of  chemical  theory. 

The  relations  of  heat  to  chemical  phenomena 
are  so  obvious  and  so  intimate  that  the  study 
of  their  connection  necessarily  attracted  atten- 
tion in  very  early  times.  But  it  was  only  when 
this  study  became  quantitative  that  any  im- 
portant generalisations  became  possible.  Most 
quantitative  estimations  of  heat  depend  eventu- 
ally upon  the  thermometer;  and  thermometry 
is  indebted  to  Englishmen  in  the  first  instance 
for  attempts  to  render  the  instrument  trust- 
worthy. 

In  this  connection  may  be  mentioned  the 
names  of  Newton  and  Shuckburgh.  Brooke 
Taylor,  in  1723,  made  a  special  study  of  the 
mercurial  thermometer  as  a  measurer  of  tem- 
perature. In  other  words,  he  sought  to  discover 
•  whether  equal  differences  of  expansion  or  con- 
traction of  mercury  corresponded  to  equal 
additions  or  abstractions  of  heat.  The  results 
showed  that  the  principle  of  the  mercurial 
thermometer  is  valid  within  at  least  the  limits 
of  temperature  between  the  boiling  and  freezing- 
points  of  water.  These  experiments  were  sub- 
sequently repeated  and  confirmed  by  Cavendish, 
and,  independently,  by  Black. 

The  discovery  of  the  phenomenon  of  latent 


172  History  of  Chemistry 

heat  by  Black  some  time  prior  to  1760  marks  an 
epoch  in  the  history  of  science.  It  was  then 
for  the  first  time  clearly  recognised  that  the 
state  of  aggregation  of  a  substance  is  associated 
with  a  definite  thermal  quantity,  and  that,  in 
order  to  effect  a  change,  a  definite  amount  of 
energy,  in  the  form  of  heat,  must  be  employed. 
The  quantitative  connection  that  exists  between 
work  and  energy  was  thus  foreshadowed. 

The  doctrine  of  specific  heat  was  taught  by 
Black  in  his  lectures  at  Glasgow  between  1761 
and  1765.  The  subject  was  subsequently  in- 
vestigated experimentally  by  Irvine  between 
1765  and  1770,  and  by  Crawford  in  1779.  A 
series  of  determinations  was  published  in  1781 
by  Wilcke,  in  the  Transactions  of  the  Swedish 
Academy.  In  these  the  term  specific  caloric, 
since  changed  to  specific  heat,  was  first  used. 
About  this  time  the  determination  of  the  amount 
of  heat  required  to  raise  substances  through  a 
definite  interval  of  temperature  was  made  the 
subject  of  experiment  by  many  observers, 
notably  by  Lavoisier  and  Laplace,  who  greatly 
improved  the  calorimetric  arrangements.  The 
values  they  obtained  long  remained  the  most 
trustworthy  estimations  of  the  specific  heats  of 
substances.  Their  joint  research  had  a  further 
influence  on  the  development  of  thermo-chemis- 
try  by  indicating  the  general  experimental 
conditions  which  were  needed  to  ensure  accuracy 


Physical  Chemistry  173 

in  such  determinations.  Lavoisier  and  Laplace 
also  measured,  in  1782—1783,  the  heat  disen- 
gaged by  the  combustion  of  substances,  and 
that  evolved  during  respiration.  In  1819 
Dulong  and  Petit  pointed  out  that  the  specific 
heat  of  a  number  of  substances,  more  particu- 
larly the  metals,  were  inversely  proportional 
to  their  atomic  weights;  or,  in  other  words,  the 
product  of  the  specific  heat  into  the  atomic 
weight  was  a  constant.  The  nature  of  the 
relation  will  be  seen  from  the  following  table 
of  certain  of  the  results  obtained  by  Dulong 
and  Petit :  — 

Element.  At.  wt.  Spec.  heat.  Atomic  heat. 

Bismuth        .  .  .  208  .  .  .  0.0288  .  .  .  6.0 

Lead 207  .  .  .  0.0293  .  .  .  6.0 

Gold 197  .  .  .  0.0298  .  .  .  5.8 

Platinum      ...  195  ...  0.0314  ...  6.1 

Silver 108  ...  0.0570  ...  6.1 

Copper          ...  63  ...  0.0952  .  .  .  6.0 

Iron     ...      ...        56  ...  0.1138  ...  6.4 

It  will  be  seen  that  these  various  elements  have 
an  uniform,  or  nearly  uniform,  atomic  heat  — 
approximately  6.2  on  the  average. 

This  would  appear  to  prove  that,  as  Dulong 
and  Petit  expressed  it,  "  the  atoms  of  simple  sub- 
stances have  equal  capacities  for  heat."  The 
variations  from  a  constant  value  are  due  partly 
to  errors  of  observation,  but  more  particularly 
to  the  circumstance  that  the  substances  com- 
pared are  not  all  in  a  strictly  comparable  con- 


174  History  of  Chemistry 

dition  —  e.g.,  they  are  not  all  equally  remote 
from  their  melting  points.  It  was  shown,  more- 
over, that  the  amount  of  heat  needed  to  raise  a 
substance  through  a  definite  interval  of  tem- 
perature increased  with  the  temperature.  The 
range  of  temperature  through  which  a  deter- 
mination was  made  in  a  particular  instance 
affected,  therefore,  the  value  of  the  specific 
heat.  The  most  noteworthy  departures  from  a 
uniform  value  were  observed  to  occur  among 
the  metalloids  —  e.g.,  carbon,  the  various  modi- 
fications of  which  had  different  specific  heats 
—  and  generally  among  elements  of  low  atomic 
weight,  in  which  the  variation  of  specific  heat 
with  temperature  was  particularly  rapid. 

Nevertheless,  the  significance  of  the  general- 
isation discovered  by  Dulong  and  Petit,  in  spite 
of  its  limitations,  was  quickly  appreciated,  as  it 
was  perceived  that  a  knowledge  of  the  specific 
heat  of  an  element  might  be  of  great  value  in 
determining  its  atomic  weight.  The  immediate 
effect  was  that  a  certain  number  of  the  atomic 
weights  fixed  by  Berzelius  mainly  on  chemical 
considerations  were  required  to  be  halved. 
Although  subsequent  experience  has  proved  that 
the  law  of  Dulong  and  Petit  is  not  capable  of  the 
simple  mathematical  expression  they  gave  it,  it 
has  shown  itself  to  be  of  great  value  in  fixing 
doubtful  atomic  weights. 

Pierre   Louis  Dulong   was   born  in    1785  at 


Physical  Chemistry  175 

Rouen,  and,  after  studying  chemistry  and  phys-' 
ics  at  the  Polytechnic  School  at  Paris,  became 
its  Professor  of  Chemistry  and  subsequently  its 
Professor  of  Physics.  In  1830  he  was  made  its 
Director  of  Studies;  and  in  1832  he  became  per- 
manent Secretary  of  the  Academy  of  Sciences. 
As  a  young  man  he  worked  with  Berzelius,  with 
whom  he  made  the  first  approximately  accurate 
determination  of  the  gravimetric  composition 
of  water.  In  1811  he  discovered  the  highly 
explosive  nitrogen  chloride,  in  the  investigation  of 
which  he  was  severely  injured,  losing  an  eye  and 
several  fingers.  He  died  in  1838.  His  collabora- 
tor, Alexis  Therese  Petit,  was  born  in  1791  at 
Vesoul,  and  died,  when  holding  the  position 
of  Professor  of  Physics  at  the  Lycee  Bonaparte, 
in  1820. 

The  attempt  made  by  Neumann  to  extend 
Dulong  and  Petit 's  "law"  to  compound  sub- 
stances was  only  partially  successful.  Nor  has 
any  important  generalisation  followed  from  our 
knowledge  of  the  specific  heat  of  liquids.  Al- 
most simultaneously  with  the  publication  of 
Dulong  and  Petit's  "law, "  Mitscherlich  made 
known  the  fact  that  similarity  in  chemical  con- 
stitution is  frequently  accompanied  by  identity 
of  crystalline  form.  Boyle,  as  far  back  as  the 
middle  of  the  seventeenth  century,  had  insisted 
upon  the  importance  of  the  forms  of  crystals  in 
throwing  light  upon  the  internal  structure  of 


176  History  of  Chemistry 

bodies.  Rome  de  1'Isle  and  Hauy  had  remarked 
that  many  different  substances  had  the  same 
crystalline  form.  It  had  been  observed  that  a 
crystal  of  potash  alum  would  continue  to  grow 
and  preserve  its  shape  in  a  solution  of  ammonia 
alum;  and  similar  observations  had  been  shown 
to  occur  in  the  case  of  vitriols.  The  invention 
of  the  reflecting  gonimetej  by  Wollaston  greatly 
facilitated  the  investigation  of  such  phenomena. 
Mitscherlich  showed  that  the  phosphates  and 
arseniates  of  analogous  composition  had  the 
same  crystalline  shape,  or,  in  other  words,  were 
isomorphous.  The  same  fact  was  observed  to 
occur  in  the  case  of  the  analogously  constituted 
sulphates  and  selenates,  and  in  that  of  the  oxides 
of  magnesium  and  zinc,  etc.  The  value  of  iso- 
morphous relations  in  determining  the  group- 
relationships  of  the  elements  and  in  deducing  the 
composition  of  salts  was  at  once  recognised  by 
Berzelius,  who  styled  the  discovery  of  isomor- 
phism by  his  pupil  Mitscherlich  as  "the  most 
important  since  the  establishment  of  the  doctrine 
of  chemical  proportions."  The  quantities  of 
the  isomorphously  replacing  elements  in  a  com- 
pound were  regarded  by  him  as  a  measure  of 
their  atomic  weights ;  and  the  principle  was  sub- 
sequently constantly  employed  by  him,  when- 
ever possible,  as  a  criterion  in  fixing  their  values. 
Other  investigators  have  followed  his  example 
in  this  respect ;  and  isomorphism  is  still  regarded 


Physical  Chemistry  177 

as  an  important  consideration  in  establishing  the 
genetic  relations  of  an  element. 

Eilhard  Mitscherlich,  the  son  of  a  minister, 
was  born  in  1794  at  Neu  Ende,  near  Jever,  in 
Oldenburg,  and,  after  studying  philology  and 
oriental  languages  at  Heidelberg,  went  to  Paris, 
and  thence  to  Gottingen,  where  he  occupied 
himself  with  natural  science.  In  1818  he  re- 
paired to  Berlin  and  commenced  to  work  on 
the  arseniates  and  phosphates,  the  similarity  in 
the  crystal-forms  of  which  he  was  the  first  to 
detect.  His  friend  Gustav  Rose,  the  mineralo- 
gist, thereupon  instructed  him  in  the  methods 
of  crystallography,  to  enable  him  to  verify  his 
discovery  and  to  establish  it  by  goniometric 
measurements.  In  1821  he  joined  Berzelius  at 
Stockholm,  where  he  pursued  his  inquiries  on 
the  connection  between  crystal-form  and  chemi- 
cal composition.  It  was  at  the  suggestion  of 
Berzelius  that  he  adopted  the  term  "isomorphy  " 
to  express  this  connection  —  the  mechanical 
consequence  of  identity  of  atomic  constitution. 
In  the  same  year  he  was  appointed  Klaproth's 
successor  in  Berlin,  where  he  died  in  1863. 

Mitscherlich  also  worked  on  the  manganates 
and  permanganates,  on  selenic  acid,  on  benzene 
and  its  derivatives,  and  on  the  artificial  pro- 
duction of  minerals. 

The  study  of  the  physical  phenomena  of  gases, 
initiated  in  1660  by  Boyle's  discovery  of  the  law 


178  History  of  Chemistry 

of  gaseous  pressure,  has  greatly  contributed  to 
our  knowledge  of  their  intrinsic  nature.  Boyle 
himself  only  proved  his  law  in  the  case  of 
atmospheric  air;  but  the  observation  was  sub- 
sequently (1676)  generalised  by  Marriotte. 
Charles,  Dalton,  and  Gay  Lussac  independently 
showed  that  gases  have  the  same  rate  of 
thermal  expansion. 

That  gases  are  made  up  of  particles  possessing 
an  internal  movement  was  surmised  by  the 
Greeks;  but  experimental  evidence  for  such  a 
view  of  their  constitution  was  first  presented 
by  Thomas  Graham  in  1829-1831,  when  he 
discovered  that  gases  move,  or  are  diffused, 
at  rates  inversely  proportional  to  the  square 
roots  of  their  densities.  Observations  of  a  like 
character,  which  found  their  explanation  in 
Graham's  discovery,  had  previously  been  made 
by  Priestley,  Dobereiner,  and  Saussure.  This 
interchange  in  the  position  of  their  particles  is 
a  property  inherent  in  gases.  Inequality  of 
density  is  not  essential  to  diffusion.  Graham 
proved  this  by  connecting  together  two  vessels, 
one  containing  nitrogen  and  the  other  carbonic 
oxide,  which  have  the  same  density.  After  the 
expiration  of  a  certain  time  both  gases  were 
found  to  be  uniformly  diffused  through  the 
vessels. 

How  these  laws  were  found  to  be  interdepen- 
dent and  mutually  connected,  and  how  they  led 


Physical  Chemistry  179 

up  to  a  molecular  theory  of  gases  which  serves 
to  explain  them,  as  well  as  certain  other  gaseous 
phenomena  to  be  subsequently  noted,  will  be 
shown  in  the  second  part  of  this  work. 

By  the  end  of  the  period  with  which  we  are  con- 
cerned —  that  is,  the  middle  of  the  nineteenth 
century  —  a  considerable  body  of  information 
had  been  accumulated  as  to  the  conditions 
which  determine  the  different  states  of  aggrega- 
tion of  matter  —  that  is,  the  conditions  which 
allow  of  the  passage  of  the  gaseous  state  into 
that  of  the  liquid,  and  of  the  liquid  into  that 
of  the  solid.  That  the  same  substance  was 
capable  of  existence  in  the  three  states  of  gas, 
liquid,  and  solid  was  of  course  evident  from  the 
case  of  water.  Even  the  most  primitive  races 
must  have  realised  that  steam,  dew,  rain,  snow, 
hail,  and  ice  were  only  modifications  of  one  and 
the  same  substance.  As  knowledge  increased, 
other  substances  came  to  be  known  which 
resembled  water  in  their  capacity  for  existence 
in  various  physical  states.  It  was  but  natural 
to  assume  that  this  was  a  general  attribute,  and 
that  all  substances  would,  sooner  or  later,  be 
found  capable  of  existence  in  each  of  the  different 
conditions  of  aggregation. 

Attempts  were  made  during  the  first  quarter 
of  the  last  century  to  prove  that  all  the  aeriform 
bodies  then  known  were  simply  vapours  more  or 
less  remote  from  their  point  of  liquefaction,  and 


180  History  of  Chemistry 

still  further  removed  from  their  point  of  conge- 
lation. Monge  and  Clouet  condensed  sulphur 
dioxide  some  time  before  1800;  and  Northmore, 
in  1805,  liquefied  chlorine.  But  these  observa- 
tions attracted  little  attention  until  Faraday, 
in  1823,  independently  effected  the  liquefaction 
of  chlorine,  and  Davy  that  of  hydrochloric  acid. 
Faraday  almost  immediately  afterwards  liquefied 
sulphur  dioxide,  sulphuretted  hydrogen,  carbon 
dioxide,  euchlorine,  nitrous  oxide,  cyanogen, 
and  ammonia. 

Other  experimenters,  among  whom  may  be 
mentioned  Thilorier  and  Natterer,  greatly  im- 
proved the  mechanical  appliances  for  liquefying 
these  gases;  liquid  carbonic  acid  and  nitrous 
oxide  were  obtained  in  considerable  quantities, 
and  employed  in  the  production  of  cold.  Cer- 
tain of  the  gases  —  hydrogen,  oxygen,  nitrogen, 
nitric  oxide,  carbonic  oxide,  etc.  —  resisted  all 
attempts  to  liquefy  them;  and  hence  gaseous 
substances  came  to  be  classified  as  permanent  and 
non-permanent,  depending  upon  whether  they 
could  or  could  not  be  liquefied.  The  division 
was  felt  to  be  irrational  even  at  the  time  it  was 
made.  There  seemed  no  a  priori  reason  why 
carbon  dioxide  and  nitrous  oxide  should  be 
liquefiable,  while  carbonic  oxide  and  nitric 
oxide  should  resist  all  attempts  to  coerce  them 
into  changing  their  state.  The  real  clue  to  the 
conditions  required  to  effect  the  liquefaction  of 


Physical  Chemistry  181 

a  gas  was  not  discovered  until  nearly  half  a 
century  later,  when,  as  will  be  shown  subse- 
quently, the  arbitrary  division  of  gases  into 
permanent  and  non-permanent  was  swept  away. 

The  discovery  of  the  law  of  gaseous  combina- 
tion by  Gay  Lussac,  and  the  recognition  by 
Ampere  and  Avogadro  of  the  delation  between 
the  density  of  a  gas  or  a  vapour  and  its  atomic 
weight,  early  led  to  improvements  in  the  methods 
of  determining  the  absolute  weights  of  gases  and 
vapours,  especially  by  French  chemists.  Both 
Gay  Lussac  and  Dumas  devised  processes  for 
determining  vapour  densities  which  were  in  use 
until  late  in  the  century,  and  which,  although 
now  superseded  by  more  convenient  and  more 
rapid  modifications  afforded  valuable  infor- 
mation concerning  the  molecular  weights  of 
substances  and  the  phenomena  of  gaseous 
dissociation. 

During  the  first  decade  of  the  nineteenth 
century  Dalton  and  Henry  discovered  the  simple 
law  which  connects  pressure  with  the  solubility 
of  a  gas  in  any  solvent  upon  which  it  exerts  no 
specific  action.  Dalton  further  developed  the 
law  so  as  to  include  the  absorption  by  a  solvent 
of  the  several  constituents  of  a  gaseous  mixture. 

Attempts  were  made  by  Schroder,  Kopp,  and 
others,  to  discover  relations  between  the  weights 
of  unit  volumes  of  liquids  and  solids  and  their 
chemical  nature;  but  such  attempts  were  only 


182  History  of  Chemistry 

partially  successful,  owing  to  the  difficulty  of 
finding  valid  conditions  of  comparison.  By 
comparing  the  specific  gravities  of  liquids  at 
their  boiling-points  Kopp  succeeded  in  detecting 
a  number  of  regularities  among  their  specific 
volumes  which  seem  to  indicate  that  a  compre- 
hensive generalisation  connecting  them  may  yet 
be  discovered.  Kopp  has  also  shown  that 
regularities  exist  among  the  boiling-points  of 
correlated  substances,  and  that  there  is  an 
interdependence  between  the  temperature  of 
their  ebullition  and  the  chemical  characters  of 
compounds. 

This  short  summary  will  suffice  to  show  that 
attempts  to  discover  relations  between  the 
physical  attributes  of  substances  and  their 
chemical  nature  were  made  more  or  less  sporadi- 
cally from  the  time  that  chemistry  was  pursued 
in  the  spirit  of  science.  But  it  is  only  in  recent 
times  that  any  great  accession  to  knowledge 
has  resulted  from  such  efforts.  The  science  of 
physical  chemistry  is  practically  a  creation  of 
our  own  period.  Its  systematic  study  may  be 
said  to  date  only  from  the  last  quarter  of  the 
nineteenth  century,  since  which  time  it  has 
made  extraordinary  progress.  Its  broad  fea- 
tures will  be  dealt  with  in  the  second  volume  of 
this  work. 


BIBLIOGRAPHY 

RELATING  TO  THE  PERIOD  COVERED  BY  VOL.  I. 


Agricola,  Georg.     De  Re  Metallica. 

Agricola,  Georg.  Vom  Bergwerck  XII.  Bucher 
darinn  mit  sch'oner  Figuren,  etc. 

Alembic  Club,  Publications  of  the.  W.  Clay, 
Edinburgh. 

Beddoes,  Thomas.  Chemical  Essays  of  Scheele. 
Murray,  London,  1786. 

Berthelot,  Marcellin.  La  Chimie  des  Anciens  et 
du  Moyenage.  Steinheil,  Paris,  1889. 

Berthelot,  Marcellin.  La  Revolution  Chirnique. 
Felix  Alcan,  Paris,  1890. 

Berthollet,  C.  L.  Essai  de  Statique  Chimique. 
Firmin  Didot,  Paris,  1803. 

Birch,  Thomas.  Life  of  Boyle.  Millar,  London, 
1744- 

Boerhaave,  Hermann.  New*  Method  of  Chemis- 
try. Shaw  and  Chambers,  London,  1727. 

Boulton,  Richard.  Boyle's  Works  Epitomised. 
Phillips  and  Taylor,  London,  1699. 

Burton,  W.  Life  of  Boerhaave.  Lintot,  London, 
1746. 

Dalton,  John.  A  New  System  of  Chemical 
Philosophy.  Two  Vols.  Bickerstaff,  London,  1807- 
1810. 

Davy,  John.  Life  of  Sir  Humphry  Davy.  Long- 
mans, London,  1836. 

Davy,  Humphry.  Collected  Works.  Edited  by 
John  Davy.  Smith,  Elder,  and  Co,,  London,  1839. 

'83 


184  History  of  Chemistry 

Figuier,  Louis.  LAlchimie  et  les  Alchimistes 
Victor  Lecon,  Paris,  1855. 

Gay  Lussac  and  Thenard.  Recherches  Physico- 
Chimiques.  Deterville,  Paris,  1811. 

Gerding,  Th.  Geschichte  der  Cheniie.  Zweite 
Ausgabe.  Grunow,  Leipzig,  1869. 

Grimaux,  Edouard.  Lavoisier,  1743-1794.  Felix 
Alcan,  Paris,  1888. 

Henry,  William  Charles.  Life  of  Dalton.  Caven- 
dish Society,  London,  1854. 

Hoefer,  Ferdinand.  Histoire  de  la  Chimie.  Two 
vols.,  Deuxieme  edition.  Firmin  Didot  Freres, 
Paris,  1866. 

Jones,  Bence.  Life  and  Letter st  of  Faraday. 
Longmans,  London,  1870. . 

Kopp,  Hermann.  Geschichte  der  Chemie.  Four 
vols.  Braunschweig,  1843-47. 

Kopp,  Hermann.  Die  Alchemie  in  'alter er  und 
neuerer  Zeit. -Heidelberg,  1886. 

Ladenberg,  Albert.*  History  of  Chemistry  Since 
the  Time  of  Lavoisier.  Translated  by  Leonard 
Dobbin.  Alembic  Club,  Edinburgh,  1900. 

Lavoisier.  Complete  Works.  Edited  by  Dumas. 
Four  vols.  Paris,  ^864. 

Lemery,  Nicolas.     C our s  de  Chimie.    Paris,  1675. 

Meyer,  Ernst  v.  History  of  Chemistry.  Trans- 
lated by  George  M'Gowan.  Macmillian  and  Co., 
London,  1891. 

Nordenskiold,  A.  E.  Carl  Wilhelm  Scheele. 
Norsledt  and  Soner,  Stockholm. 

Ostwald's  Klassiker  der  Exakten  Wissenschaften. 

Paris,  John  Ayrton.  Life  of  Sir  Humphry  Davy. 
Colbourne  and  Bentley,  London,  1831. 

Priestley,  Joseph.  Experiments  and  Observa- 
tions on  Different  Kinds  of  Air.  Six  vols.  J.  John- 
son, London,  1775  et  seq. 


Bibliography  185 

Roscoe,  H.  E.,  and  Harden,  A.  A  New  View 
of  the  Origin  of  Dalton's  Atomic  Theory.  Mac- 
millian  and  Co.,  London. 

Schmieder.    Geschichte  der  Alchimie.    Halle,  1832. 

Schubert,  E.,  und  Sudhoff,  K.  Paracelsus'  s 
Forschungen.  Frankfurt,  1887-89. 

Shaw,  Peter.  StahVs  Chemistry.  Osborn  and 
Longman,  London. 

Stahl,  G.  E.     Cheimia  Rationalis  (1720). 

Stahl,   G.   E.     Zymotechnia  Fundamentalis,  etc. 


Stange,  Albert.  Zeitalter  der  Chemie.  Otto 
Wigand,  Leipzig,  1908. 

Thomson,  Thomas.  History  of  Chemistry.  Two 
vols.  Colbourne  and  Bentley,  London,  1830. 

Thorpe,  T.  E.  Essays  in  Historical  Chemistry. 
,  Second  edition.  Macmillian  and  Co.,  London,  1902. 

Thorpe,  T.  E.  Humphry  Davy,  Poet  and 
Philosopher.  Cassells,  London,  1895. 

Thorpe,  T.  E.  Joseph  Priestley.  Dent  and  Co., 
London,  1906. 

Wilson,  George.  Life  of  Cavendish.  Cavendish 
Society,  London  >  1851. 


INDEX 


GAR^EUS 35 

Agricola,  Georg 66 

Aidoneous,  god  of  earth 22 

Albertus  Magnus 40,  47 

Alchemy 28 

and  astrology 36 

its  character 39 

Alkahest 51 

Anastatius  the  Sinaite 35 

Anaxagoras 26 

Anaximenes 21 

Aqua  regia 39 

Arabian  learning,  influence  on  Western  Europe.  .  25 

Archaeus 5-9 

Argentarium i  o 

A  rgentum  vivum 1 1 

Aristotle,  his  doctrine  of  "elements" 23 

his  character  as  a  man  of  science 24 

Arnoldus  Villanovanus  (Arnaud  de  Villeneuve) 

42,  47,  48,  51 

Arvidson 155 

Arrenichon 13 

Ars  Transmutatoria 46 

Artephius 49 

Astrology  and  alchemy 36 

Atoms,  ancient  theories  of 26 

Atramentum 14 

Aurichalcum 9 

Auripigmentum  (orpiment) 13 

Averroes 2 5 ,  38 

Avicenna 38 

A  vogadro 1 8 1 

Bacon,  Roger 40,  41 


i88  Index 


Bacon,  Lord 55 

Baldwin's  phosphorus 80 

Bartoletti,  Fabrizio 155 

Basil  Valentine 43,  47,  49,  156 

Bathurst,  Ralph 74 

Becher,  John  Joachim 81,  156 

Benther,  David,  alchemist 53 

Bergman 94,  107,  124,  158,  160 

Berigard  de  Pisa 48 

Berthollat,  Claude  Louis 116  et  seq.,  156,  160,  164 

Berthelot 37 

Berzelius,  Jons  Jakob X33>  J5^,  X59,  160,  164 

Black,  Joseph 98  et  seq.,  171 

Bochart 4 

Boerhaave 3—20,  35,  42,  49,  51,  106 

his  life  and  work 84,  et  seq. 

Bolim 1 60 

Borri 53 

Botyritis 12 

Bouillon-Lagrange 158 

Boullay 162,  167 

Boyle,  Robert ....  20,  72  et  seq.,  107,  113,  155,  157,  159, 

175.  X77 

Bragadino,  alchemist 53 

Brooke  Taylor 171 

Brugnatelli 158,  161 

Cadmia 12 

C&ruleum 12 

Caligula 34 

Carbunculus 48 

Cardan no 

Cavendish 94,  102  'et  seq.,  107,  171 

Caventou 162 

Cerium,  its  discovery 121 

Cerussa 10 

usta 12 

Chalcantum  (copper  sulphate) 12 

Charles 178 

Chalybes,  smelters  of  iron 1 1 

Chemistry  of  the  ancients i 

Chenevix 157 

Chevreul 54,  162 

Chlorine,  discovery  of 107 

Chromium,  discovery  of 120 

Chrysocolla 12 


Index  189 


Cinnabar,  use  as  pigment 13 

Clouet 180 

Clytemius,  John 54 

Cobalt,  discovered  by  Brandt 107 

Combining  proportion 129 

Conservation  of  matter 113 

Conringius,  Hermann 51 

Copper,  Egyptian 8 

Roman 9 

Cordus  Valerius 69 

Crawford 107,172 

Croll,  Oswald 65 

Cronstedt 107 

Cyanogen,  discovery  of 151 

Dalton 125  et  seq.,  178,  181 

Davy * 29,  141 

Dee,  John 53 

Delambre 1 16 

Demokritos 26 

De  Re  Metallica 66 

Derosne 157 

Dickinson 50 

Diodorua  Siculus 7 

Dioscoiides 156,  1 60 

Dobereiner 155,  162,  167 

Dorn 60 

Duchesne 6 1 

Duhamel 98,157 

Dumas 162,167,168,181 

Dulong 158,  173,  174 

Dyeing  by  the  Egyptians 14 

Egypt,  birthplace  of  chemistry i 

Electru'm 8 

Elementa  Chemia 87 

** Elements,"  Aristotelian,  qualities  of 23 

Elephantinum 14 

Elixir 32 

Eller 94 

Empedokles 23 

Erastius,  Thomas 51 

Equivalent 129 

Fax  vini 157 

Fischer,  G.  E 124 

Flos  ceris 12 

Fourcroy 112,  118, 155, 158, 161, 162 


190  Index 


PAGE 

Frankland 168 

Gahn 1 08 

Gas  sylvestre 63 

Gay  Lussac 150,  155,  161,  164,  167,  178,  181 

Geber 36 

theory  of  metals 37,  156 

Generation  of  metals 33 

Geoffrey 106 

Gerhardt 168 

Glass,  known  to  the  ancients 15 

Glauber,  Johann  Rudolf 68 

Glucinum,  its  discovery 120 

Gmelin,  L 161 

Gold,  extraction  by  ancients 7 

Goulard 157 

Gomes .* 1 6 1 

Gottling 156 

Graham,  Thomas ' 178 

Gresham  College ; 74 

Gualdo 49 

Guyton  de  Morveau 112,160 

H&matinon 15 

Hales,  Stephen 89 

"  Harmonics,"  Paracelsian 61 

Hauy 176 

Hellot 108 

Helmont,  John  Baptist  van 63 

Helvetius 48 

Hennel 155 

Henry 181 

Herakleitos 21 

Here,  god  of  air 22 

Hermbstadt 158 

Hermes  Trismegistus 4,  33 

"  Hermes  of  Germany,  the" 52 

Hoffmann 106 

Homberg,  William ' .  . .  84 

Houton-Labillardiere 158 

Howard 161 

Hyalos,  use'of,  for  kindling  fire 15 

Hydrargyrum 1 1 

latro-chemistry f .  . . 57 

Ink  of  the  ancients 14 

Ingenhousz 21 

Invisible  College,  the 74 


Index  191 


PAGE 

Iron,  use  of,  by  the  ancients  ..................        10 

Irvine  ......................................      172 

Isaac  of  Holland  .............................        49 

Isomerism  ..................................      165 

Isomorphism,  discovery  of  ....................      176 

"  Kalid,  "  his  philosopher's  stone  ...............        48 

Key  of  Wisdom  ..........................  ....        53 

Kircher  .................  ...................        51 

Kirchhoff  ...................................      162 

Kirwan  ......  ..............................      113 

Klaproth  .................................  120,  1  60 

Klettenberg,  Hector  de  .......................        54 

Kopp  .............  .........................      181 

Krohnemann,  William  de  .............  ........        53 

Kunkel,  John  ................................  51,  79 

Labor  -atorium  Chymicum  ......................        80 

Lac  Virginis  ................................      157 

Lagrange  .  .  -.  ................................      1  1  6 

Laplace  ...............................  %••••      J  7  2 

Latent  heat  ............................  7.  .  .99,  172 

Lauraquais  .................................      155 

Laurent  ....................................      168 

Lavoisier  ...............................  20,  22,  109 

antiphlogistic  theory  .....  112,  116,  156,  164,  166,  173 

Law  of  Dulong  and  Petit  ...................  173,  174 

Law  of  electrolytic  action  .....................      153 

Lead,  known  to  the  ancients  ..................        10 

Leblanc  ....................................      108 

Lehmann  ...................................      159 

Lemery,  Nicolas  ........................  83,  154,  156 

Leo  Africanus  ...........  ....................        36 

Leukippos  ..............  ....................        26 

Libavius,  Andreas  (Libau)  ...............  62,  155,  157 

Lieber,  Thomas  .............................        65 

Liebig  ........................  155,  156,  159,  164,  167 

Lowiz.  .  .  ...................................      156 

Lucretius  ...................................  26,  27 

Lully,  Raymund  ..........................  41,  47,  49 

Macquer  ...........................  •  .........        98 

Magistery,  grand  ............................  48 

small  ....................................        48 

Magnesia  alba,  nature  of  .....................      107 

Manganese,  discovery  of  ......................      107 

Marggraf  ..........................  95,  107,  108,  157 

Marie  Ziglerin  burnt  ........................  '.  53 


192  Index 

PAGE 

Martian  preparations 37  « 

Marriotte 178 

Maternus,  Julius  Firmicus 35 

Mayerne,  Turquet  de 65 

Mayow,  John 82  et  seq. 

Medicine  and  Astrology 58 

Melinum 13—14 

Menethes  Sibonita 3 

' '  Mercury, "  as  "  element  " 31 

Mercury,  receipt  for  fixing 50 

Metallurgy  of  the  ancients 7 

Metals  of  the  phlogistians 104 

Minderer,  Raymond 157 

Minium 12 

Mitscherlich. ... 159,  175,  176,  177 

Molybdena 12 

Monge 180 

Monro,  Donald 159 

Mordants,  Egyptian 15 

Mundamus 43 

Mynsicht,  Adrian  van 65,158 

Narcotine , 161 

Natron,  used  as  a  detergent 16 

Natterer 1 80 

Nestis,  god  of  water 22 

Neumann 94,  1 7 5 

New  System  of  Chemical  Philosophy,  Dalton's. ...  129 

Nickel,  discovery  of 107 

Nitrogen,  discovery  of 107 

Northmore 180 

CErugo 12 

Oil  of  wine 155 

Okeanos 19 

Oleus  Borrichius 33 

Olimpiodorus 35 

Onychitis 12 

Operinus 60 

Ostracitis 12 

Oxides,  metallic,  used  by  ancients  to  colour  glass  15 

Oxygen,  its  discovery 105 

influence  of,  on  chemistry 105 

Palissy,  Bernard 67 

Paracelsus 40,  48,  57 

Paratonium 13 

Pelletier 162 


Index  193 


PAGE 

Peligot 162 

Peripatetic  philosophy,  influence  on  science 24 

Petit,  Alexis  Therese :  . .  173, 175 

Pherekides. 21 

Philosophic,  Orientalis 38 

Philosopher's  Stone 32,46,49 

Philosophical  egg 33 

Phlogistonism 95  et  seq. 

Phosphorus,  discovery  of 80,  107 

Placitis 12 

Platinum,  discovery  of 107 

Plato's  doctrine  of  "elements" 23 

Pliny 156 

Plumbum  album 10 

nigrum 10 

Pope  John  XXII.,  alchemist 46 

Porret 160 

Pott 94,  95,  159 

Price,  James  of  Guildford 54 

Priestley,  Joseph 20,  22 

his  life  and  work 99  et  seq. 

Proust,  Joseph  Louis 121 

Purple  of  Cassius 8 1 

Purpurissum 13 

Quintessence  of  philosophers *...  32 

Raquetaillade,  Jean  de 43 

Realgar 13 

Reaumur 108 

Rey 1 10 

Rhazes 38 

Richter,  Jeremiah  Benjamin 124 

Ripley,  George 43 

Robiquet 161,  167 

Roebuck 108 

Rome  de  L'Isle 176 

Rose,  Gustav 177 

Rosenkreutz,  Christian 55 

Rouelle 94,  106,  159 

Royal  Society,  foundation  of 74 

Rubrica 13 

Rupecissa,  Johannes  de 43 

Saccharum  plumbi  quintessential 157 

Sala,  Angelus 65 

Sal  Armoniacum 44 

Sal  Duplicatum , , , 8 1 


194  Index 


PAGE 

Sal  mirabile ,t 68 

Sandarach .* 13 

Saturnine  solutions 37 

Savary 155 

Sceptical  Chemist,  The 70 

Scheele 96  et  seq.,  107,  155,  158,  159,  160,  166 

Schroeder. 181 

Scoria  ceris 12 

Sefstrom 135 

Seguin .- 159 

Seignette,  Peter 157 

Selenium,  its  discovery 135 

Sennert,  Daniel 65 

Serturner 16 1 

Severinus 61 

Silver,  known  to  the  ancients 7 

Sinopis 13 

Soap,  manufacture  by  Gauls 15 

Specific  heat,  discovery  of .  . 99 

Spiritus  igno-aereus 82 

Stahl,  George  Ernst 92,156 

Stannum 10 

Statical  Essays^  of  Hales 89 

Statique  Chimique. 117 

Stephanus 35 

Stibium .  ; 13 

Stimmi 13 

Strontia,  discovery  of 107 

Suidas 34 

"  Sulphur, "  as  "  element " 31 

Sulzbach no 

Sun  worship 22 

Sylvius,  Francis  de  le  Boe 64 

Syncellus 35 

Tachenius 69 

Tartarus,  doctrine  of 59,  157 

Tellurium,  discovery  of 121 

Terra  pinguis  of  Becher 92 

Tertiarium 10 

Tertullian 19 

Thales  of  Miletus 19 

Thenard 152,  164 

Theophrastus 156 

The  Tincture 32 

Thilorier 180 


Index  195 

PAGE 

Thomson,  Thomas .  .* 129 

Thorium,  its  discovery 135 

Thurneysser,  Leonard 53,  60 

Tin,  known  to  the  Egyptians 9 

Transmutation 28,  30 

Trommsdorff 157 

Tubal  Cain  (Tuval-Cain) 7 

Turquet  de  Mayerne 158 

Tyrian  purple 14 

Valentine,  Basil 43,  47,  49,  T56 

Van  Helmont 20,  48,  63 

Vasa  murrhina 15 

Vauquelin 119,  155,  158,  161,  162 

Verdigris 56 

Vincent  de  Beauvais 50 

Von  Ittner ' 160 

Wallis,  John 74 

Ward,  Seth 74 

"White"  gold 7 

Wilcke 172 

Willis,  Thomas 64,  74 

Wohler 161,  163,  167 

Wollaston 144,  176 

Woodward 160 

Wray 159 

Wren,  Christopher 74 

Zacharias,  Daniel 49 

Zozimus  the  Panopolite 4 


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